What is the Target in Bitcoin? | Bitcoin Mining Explained
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Target The number you need to get below to mine a block.

The target is used in mining. It is a number that a block hash must be below for the block to be added on to the blockchain.

The target adjusts every 2016 blocks (roughly two weeks) to try and ensure that blocks are mined once every 10 minutes on average. It therefore creates a consistent time between blocks and a consistent issuance of new bitcoins in to the network (via the block reward).

To compensate for increasing hardware speed and varying interest in running nodes over time, the proof-of-work difficulty is determined by a moving average targeting an average number of blocks per hour. If they’re generated too fast, the difficulty increases. – Satoshi Nakamoto

Current target:

000000000000000000122cbc0000000000000000000000000000000000000000

Block 619,353

The target is in hexadecimal, but it’s still a number.

1. When does the target adjust?

The target adjusts on every 2016th block. This is roughly every two weeks (because there are 20,160 minutes in a two-week period).

Here are the dates and target values for every target adjustment in Bitcoin’s history:

Bitcoin Target History

0 03 Jan 2009, 18:15:05 00000000ffff0000000000000000000000000000000000000000000000000000
2,016 27 Jan 2009, 13:38:51 00000000ffff0000000000000000000000000000000000000000000000000000
4,032 12 Feb 2009, 19:16:30 00000000ffff0000000000000000000000000000000000000000000000000000
6,048 02 Mar 2009, 04:01:53 00000000ffff0000000000000000000000000000000000000000000000000000
8,064 20 Mar 2009, 00:26:26 00000000ffff0000000000000000000000000000000000000000000000000000
10,080 06 Apr 2009, 22:04:23 00000000ffff0000000000000000000000000000000000000000000000000000
12,096 24 Apr 2009, 18:51:38 00000000ffff0000000000000000000000000000000000000000000000000000
14,112 12 May 2009, 03:20:25 00000000ffff0000000000000000000000000000000000000000000000000000
16,128 31 May 2009, 02:31:25 00000000ffff0000000000000000000000000000000000000000000000000000
18,144 26 Jun 2009, 21:32:53 00000000ffff0000000000000000000000000000000000000000000000000000
20,160 25 Jul 2009, 00:30:16 00000000ffff0000000000000000000000000000000000000000000000000000
22,176 04 Sep 2009, 13:01:38 00000000ffff0000000000000000000000000000000000000000000000000000
24,192 02 Oct 2009, 03:27:08 00000000ffff0000000000000000000000000000000000000000000000000000
26,208 31 Oct 2009, 15:28:20 00000000ffff0000000000000000000000000000000000000000000000000000
28,224 27 Nov 2009, 21:51:07 00000000ffff0000000000000000000000000000000000000000000000000000
30,240 18 Dec 2009, 09:56:01 00000000ffff0000000000000000000000000000000000000000000000000000
32,256 30 Dec 2009, 06:11:04 00000000d86a0000000000000000000000000000000000000000000000000000
34,272 11 Jan 2010, 22:48:37 00000000c4280000000000000000000000000000000000000000000000000000
36,288 25 Jan 2010, 13:07:59 00000000be710000000000000000000000000000000000000000000000000000
38,304 04 Feb 2010, 21:43:14 000000008cc30000000000000000000000000000000000000000000000000000
40,320 14 Feb 2010, 23:52:59 0000000065465700000000000000000000000000000000000000000000000000
42,336 24 Feb 2010, 08:41:04 0000000043b3e500000000000000000000000000000000000000000000000000
44,352 08 Mar 2010, 01:14:33 00000000387f6f00000000000000000000000000000000000000000000000000
46,368 21 Mar 2010, 22:54:24 0000000038137500000000000000000000000000000000000000000000000000
48,384 01 Apr 2010, 11:07:22 000000002a111500000000000000000000000000000000000000000000000000
50,400 12 Apr 2010, 08:39:46 0000000020bca700000000000000000000000000000000000000000000000000
52,416 21 Apr 2010, 21:52:52 0000000016546f00000000000000000000000000000000000000000000000000
54,432 04 May 2010, 09:46:16 0000000013ec5300000000000000000000000000000000000000000000000000
56,448 19 May 2010, 14:13:55 00000000159c2400000000000000000000000000000000000000000000000000
58,464 29 May 2010, 13:57:28 000000000f675c00000000000000000000000000000000000000000000000000
60,480 11 Jun 2010, 23:26:26 000000000eba6400000000000000000000000000000000000000000000000000
62,496 24 Jun 2010, 12:27:26 000000000d314200000000000000000000000000000000000000000000000000
64,512 06 Jul 2010, 01:57:44 000000000ae49300000000000000000000000000000000000000000000000000
66,528 13 Jul 2010, 08:03:57 0000000005a3f400000000000000000000000000000000000000000000000000
68,544 16 Jul 2010, 16:29:39 000000000168fd00000000000000000000000000000000000000000000000000
70,560 27 Jul 2010, 02:42:38 00000000010c5a00000000000000000000000000000000000000000000000000
72,576 05 Aug 2010, 19:46:35 0000000000ba1800000000000000000000000000000000000000000000000000
74,592 15 Aug 2010, 11:11:11 0000000000800e00000000000000000000000000000000000000000000000000
76,608 26 Aug 2010, 23:13:23 0000000000692098000000000000000000000000000000000000000000000000
78,624 08 Sep 2010, 05:04:49 00000000005bede6000000000000000000000000000000000000000000000000
80,640 19 Sep 2010, 02:04:07 00000000004766ed000000000000000000000000000000000000000000000000
82,656 28 Sep 2010, 19:58:28 000000000031b2a3000000000000000000000000000000000000000000000000
84,672 12 Oct 2010, 05:35:05 00000000002f8e9d000000000000000000000000000000000000000000000000
86,688 21 Oct 2010, 05:13:15 00000000001e7eca000000000000000000000000000000000000000000000000
88,704 30 Oct 2010, 22:58:47 0000000000153263000000000000000000000000000000000000000000000000
90,720 09 Nov 2010, 12:29:28 00000000000e7256000000000000000000000000000000000000000000000000
92,736 18 Nov 2010, 18:44:34 0000000000098b2a000000000000000000000000000000000000000000000000
94,752 30 Nov 2010, 16:37:55 0000000000081cd2000000000000000000000000000000000000000000000000
96,768 09 Dec 2010, 22:20:02 0000000000055953000000000000000000000000000000000000000000000000
98,784 21 Dec 2010, 18:34:03 000000000004864c000000000000000000000000000000000000000000000000
100,800 03 Jan 2011, 05:10:11 00000000000404cb000000000000000000000000000000000000000000000000
102,816 15 Jan 2011, 14:26:07 0000000000038dee000000000000000000000000000000000000000000000000
104,832 27 Jan 2011, 08:16:11 000000000002fa29000000000000000000000000000000000000000000000000
106,848 08 Feb 2011, 04:53:20 0000000000028552000000000000000000000000000000000000000000000000
108,864 18 Feb 2011, 05:15:52 000000000001cc26000000000000000000000000000000000000000000000000
110,880 27 Feb 2011, 09:59:20 0000000000012dcd000000000000000000000000000000000000000000000000
112,896 09 Mar 2011, 15:25:55 000000000000dc31000000000000000000000000000000000000000000000000
114,912 25 Mar 2011, 02:39:45 000000000000f339000000000000000000000000000000000000000000000000
116,928 05 Apr 2011, 20:09:57 000000000000cbbd000000000000000000000000000000000000000000000000
118,944 18 Apr 2011, 07:49:36 000000000000b5ac000000000000000000000000000000000000000000000000
120,960 30 Apr 2011, 02:53:00 00000000000098fa000000000000000000000000000000000000000000000000
122,976 09 May 2011, 21:17:24 0000000000006a93b30000000000000000000000000000000000000000000000
124,992 18 May 2011, 22:04:47 00000000000044b9f20000000000000000000000000000000000000000000000
127,008 26 May 2011, 18:41:56 0000000000002694210000000000000000000000000000000000000000000000
129,024 06 Jun 2011, 12:25:05 0000000000001d932f0000000000000000000000000000000000000000000000
131,040 15 Jun 2011, 13:49:34 0000000000001321850000000000000000000000000000000000000000000000
133,056 24 Jun 2011, 11:45:23 0000000000000c2a120000000000000000000000000000000000000000000000
135,072 06 Jul 2011, 20:35:46 0000000000000abbcf0000000000000000000000000000000000000000000000
137,088 19 Jul 2011, 19:23:09 00000000000009ec040000000000000000000000000000000000000000000000
139,104 01 Aug 2011, 08:11:19 00000000000008e1e50000000000000000000000000000000000000000000000
141,120 15 Aug 2011, 23:44:54 000000000000094a860000000000000000000000000000000000000000000000
143,136 30 Aug 2011, 05:15:03 000000000000096fe30000000000000000000000000000000000000000000000
145,152 13 Sep 2011, 09:31:56 000000000000098ea50000000000000000000000000000000000000000000000
147,168 27 Sep 2011, 22:47:04 00000000000009ee5d0000000000000000000000000000000000000000000000
149,184 14 Oct 2011, 01:44:35 0000000000000b6d4b0000000000000000000000000000000000000000000000
151,200 31 Oct 2011, 03:42:14 0000000000000df0ca0000000000000000000000000000000000000000000000
153,216 14 Nov 2011, 06:56:10 0000000000000e119a0000000000000000000000000000000000000000000000
155,232 29 Nov 2011, 14:20:20 0000000000000f61b10000000000000000000000000000000000000000000000
157,248 12 Dec 2011, 19:42:35 0000000000000e86680000000000000000000000000000000000000000000000
159,264 26 Dec 2011, 18:43:25 0000000000000e76ba0000000000000000000000000000000000000000000000
161,280 08 Jan 2012, 18:26:16 0000000000000d69d70000000000000000000000000000000000000000000000
163,296 22 Jan 2012, 03:55:04 0000000000000cd43f0000000000000000000000000000000000000000000000
165,312 04 Feb 2012, 10:32:41 0000000000000c290b0000000000000000000000000000000000000000000000
167,328 18 Feb 2012, 11:24:15 0000000000000c309c0000000000000000000000000000000000000000000000
169,344 02 Mar 2012, 08:25:36 0000000000000b350c0000000000000000000000000000000000000000000000
171,360 16 Mar 2012, 08:09:54 0000000000000b32870000000000000000000000000000000000000000000000
173,376 29 Mar 2012, 05:41:47 0000000000000a507e0000000000000000000000000000000000000000000000
175,392 12 Apr 2012, 16:04:49 0000000000000aa1e30000000000000000000000000000000000000000000000
177,408 27 Apr 2012, 07:39:30 0000000000000b1ef70000000000000000000000000000000000000000000000
179,424 09 May 2012, 12:08:33 00000000000009ae020000000000000000000000000000000000000000000000
181,440 24 May 2012, 18:10:29 0000000000000a8b5f0000000000000000000000000000000000000000000000
183,456 07 Jun 2012, 20:05:25 0000000000000a98d60000000000000000000000000000000000000000000000
185,472 20 Jun 2012, 16:16:04 00000000000009b78a0000000000000000000000000000000000000000000000
187,488 04 Jul 2012, 11:37:21 0000000000000994310000000000000000000000000000000000000000000000
189,504 17 Jul 2012, 14:59:26 00000000000008fd2e0000000000000000000000000000000000000000000000
191,520 30 Jul 2012, 11:26:17 000000000000083cc90000000000000000000000000000000000000000000000
193,536 12 Aug 2012, 12:00:55 00000000000007a85e0000000000000000000000000000000000000000000000
195,552 25 Aug 2012, 01:46:39 00000000000006dfbe0000000000000000000000000000000000000000000000
197,568 06 Sep 2012, 18:10:37 000000000000063a380000000000000000000000000000000000000000000000
199,584 19 Sep 2012, 22:14:11 00000000000005db8b0000000000000000000000000000000000000000000000
201,600 03 Oct 2012, 01:11:00 000000000000057e080000000000000000000000000000000000000000000000
203,616 16 Oct 2012, 22:56:08 0000000000000575ef0000000000000000000000000000000000000000000000
205,632 30 Oct 2012, 00:16:35 0000000000000513c50000000000000000000000000000000000000000000000
207,648 12 Nov 2012, 17:59:46 00000000000004faeb0000000000000000000000000000000000000000000000
209,664 26 Nov 2012, 11:10:29 00000000000004e0ea0000000000000000000000000000000000000000000000
211,680 10 Dec 2012, 18:03:33 00000000000004fa620000000000000000000000000000000000000000000000
213,696 26 Dec 2012, 14:05:40 00000000000005a16b0000000000000000000000000000000000000000000000
215,712 08 Jan 2013, 10:40:34 0000000000000529b10000000000000000000000000000000000000000000000
217,728 23 Jan 2013, 18:41:27 00000000000005a6b10000000000000000000000000000000000000000000000
219,744 05 Feb 2013, 11:19:06 000000000000051f3c0000000000000000000000000000000000000000000000
221,760 18 Feb 2013, 00:47:50 00000000000004985c0000000000000000000000000000000000000000000000
223,776 01 Mar 2013, 17:42:44 00000000000003d74b0000000000000000000000000000000000000000000000
225,792 14 Mar 2013, 08:32:26 0000000000000375fa0000000000000000000000000000000000000000000000
227,808 24 Mar 2013, 12:00:25 00000000000002816e0000000000000000000000000000000000000000000000
229,824 05 Apr 2013, 17:40:43 000000000000022fbe0000000000000000000000000000000000000000000000
231,840 17 Apr 2013, 17:02:14 00000000000001de940000000000000000000000000000000000000000000000
233,856 30 Apr 2013, 04:34:31 00000000000001aa3d0000000000000000000000000000000000000000000000
235,872 12 May 2013, 19:15:23 000000000000017fe90000000000000000000000000000000000000000000000
237,888 25 May 2013, 16:35:46 0000000000000161640000000000000000000000000000000000000000000000
239,904 05 Jun 2013, 14:25:18 0000000000000113370000000000000000000000000000000000000000000000
241,920 16 Jun 2013, 21:37:34 00000000000000de150000000000000000000000000000000000000000000000
243,936 29 Jun 2013, 14:22:05 00000000000000c94e0000000000000000000000000000000000000000000000
245,952 11 Jul 2013, 00:22:43 00000000000000a4290000000000000000000000000000000000000000000000
247,968 22 Jul 2013, 17:57:07 0000000000000089680000000000000000000000000000000000000000000000
249,984 03 Aug 2013, 10:51:55 0000000000000072dbf200000000000000000000000000000000000000000000
252,000 13 Aug 2013, 18:11:30 0000000000000054873200000000000000000000000000000000000000000000
254,016 24 Aug 2013, 14:08:39 0000000000000041525700000000000000000000000000000000000000000000
256,032 04 Sep 2013, 04:21:00 0000000000000031679c00000000000000000000000000000000000000000000
258,048 14 Sep 2013, 23:44:08 0000000000000026222200000000000000000000000000000000000000000000
260,064 25 Sep 2013, 14:09:06 000000000000001cdc2000000000000000000000000000000000000000000000
262,080 06 Oct 2013, 14:42:32 0000000000000016b0ca00000000000000000000000000000000000000000000
264,096 16 Oct 2013, 12:16:28 00000000000000100ab600000000000000000000000000000000000000000000
266,112 26 Oct 2013, 02:24:32 000000000000000afc8500000000000000000000000000000000000000000000
268,128 05 Nov 2013, 19:52:03 000000000000000867f300000000000000000000000000000000000000000000
270,144 17 Nov 2013, 14:44:59 00000000000000070bfb00000000000000000000000000000000000000000000
272,160 29 Nov 2013, 16:30:48 0000000000000006124200000000000000000000000000000000000000000000
274,176 10 Dec 2013, 14:11:26 0000000000000004ba6e00000000000000000000000000000000000000000000
276,192 21 Dec 2013, 09:11:52 0000000000000003a30c00000000000000000000000000000000000000000000
278,208 02 Jan 2014, 00:58:38 0000000000000003071f00000000000000000000000000000000000000000000
280,224 13 Jan 2014, 03:20:20 0000000000000002666600000000000000000000000000000000000000000000
282,240 24 Jan 2014, 13:28:46 0000000000000001f52c00000000000000000000000000000000000000000000
284,256 05 Feb 2014, 07:14:16 0000000000000001a36e00000000000000000000000000000000000000000000
286,272 17 Feb 2014, 00:43:59 00000000000000015f5300000000000000000000000000000000000000000000
288,288 28 Feb 2014, 12:29:45 0000000000000001202600000000000000000000000000000000000000000000
290,304 13 Mar 2014, 02:12:44 000000000000000102b100000000000000000000000000000000000000000000
292,320 24 Mar 2014, 23:30:32 0000000000000000db9900000000000000000000000000000000000000000000
294,336 05 Apr 2014, 10:41:18 0000000000000000b3aa00000000000000000000000000000000000000000000
296,352 17 Apr 2014, 17:27:26 00000000000000009d8c00000000000000000000000000000000000000000000
298,368 29 Apr 2014, 22:39:35 0000000000000000896c00000000000000000000000000000000000000000000
300,384 12 May 2014, 14:18:31 00000000000000007c3053000000000000000000000000000000000000000000
302,400 24 May 2014, 10:52:30 0000000000000000692842000000000000000000000000000000000000000000
304,416 05 Jun 2014, 21:49:53 00000000000000005d859a000000000000000000000000000000000000000000
306,432 18 Jun 2014, 03:14:40 000000000000000051aba2000000000000000000000000000000000000000000
308,448 29 Jun 2014, 08:12:36 0000000000000000415fd1000000000000000000000000000000000000000000
310,464 12 Jul 2014, 22:58:14 00000000000000003f6be6000000000000000000000000000000000000000000
312,480 25 Jul 2014, 21:51:32 00000000000000003aaea2000000000000000000000000000000000000000000
314,496 08 Aug 2014, 05:01:52 000000000000000037ba62000000000000000000000000000000000000000000
316,512 19 Aug 2014, 19:11:58 00000000000000002e1c58000000000000000000000000000000000000000000
318,528 31 Aug 2014, 23:19:12 00000000000000002815ee000000000000000000000000000000000000000000
320,544 13 Sep 2014, 20:08:16 000000000000000024dbe9000000000000000000000000000000000000000000
322,560 25 Sep 2014, 21:21:20 00000000000000001fb893000000000000000000000000000000000000000000
324,576 09 Oct 2014, 18:04:26 00000000000000001f6973000000000000000000000000000000000000000000
326,592 23 Oct 2014, 09:09:53 00000000000000001e8dc0000000000000000000000000000000000000000000
328,608 05 Nov 2014, 02:30:31 00000000000000001bc330000000000000000000000000000000000000000000
330,624 18 Nov 2014, 21:12:04 00000000000000001b4861000000000000000000000000000000000000000000
332,640 02 Dec 2014, 23:41:45 00000000000000001b7b74000000000000000000000000000000000000000000
334,656 17 Dec 2014, 04:37:04 00000000000000001bdd7c000000000000000000000000000000000000000000
336,672 30 Dec 2014, 18:53:08 00000000000000001b0dca000000000000000000000000000000000000000000
338,688 12 Jan 2015, 17:34:33 000000000000000019012f000000000000000000000000000000000000000000
340,704 27 Jan 2015, 15:35:46 00000000000000001aa3c0000000000000000000000000000000000000000000
342,720 09 Feb 2015, 15:40:15 000000000000000018bb87000000000000000000000000000000000000000000
344,736 22 Feb 2015, 23:48:57 0000000000000000178d3a000000000000000000000000000000000000000000
346,752 08 Mar 2015, 18:42:45 0000000000000000172ec0000000000000000000000000000000000000000000
348,768 22 Mar 2015, 23:53:31 00000000000000001788f2000000000000000000000000000000000000000000
350,784 05 Apr 2015, 05:22:25 0000000000000000163c71000000000000000000000000000000000000000000
352,800 19 Apr 2015, 18:25:06 00000000000000001717f0000000000000000000000000000000000000000000
354,816 03 May 2015, 18:22:21 00000000000000001713dd000000000000000000000000000000000000000000
356,832 17 May 2015, 10:27:13 00000000000000001686f5000000000000000000000000000000000000000000
358,848 31 May 2015, 19:06:25 0000000000000000171a8b000000000000000000000000000000000000000000
360,864 14 Jun 2015, 04:56:03 0000000000000000162043000000000000000000000000000000000000000000
362,880 28 Jun 2015, 07:07:26 000000000000000016418e000000000000000000000000000000000000000000
364,896 11 Jul 2015, 20:24:46 00000000000000001586c8000000000000000000000000000000000000000000
366,912 25 Jul 2015, 12:44:45 0000000000000000150815000000000000000000000000000000000000000000
368,928 08 Aug 2015, 10:15:30 000000000000000014dd04000000000000000000000000000000000000000000
370,944 22 Aug 2015, 00:49:43 00000000000000001443c4000000000000000000000000000000000000000000
372,960 04 Sep 2015, 09:05:07 0000000000000000134dc1000000000000000000000000000000000000000000
374,976 17 Sep 2015, 19:50:04 00000000000000001287ba000000000000000000000000000000000000000000
376,992 01 Oct 2015, 11:53:10 0000000000000000121472000000000000000000000000000000000000000000
379,008 15 Oct 2015, 11:32:31 0000000000000000120f14000000000000000000000000000000000000000000
381,024 29 Oct 2015, 04:25:06 000000000000000011a954000000000000000000000000000000000000000000
383,040 11 Nov 2015, 10:11:32 000000000000000010b289000000000000000000000000000000000000000000
385,056 24 Nov 2015, 02:34:22 00000000000000000f1e76000000000000000000000000000000000000000000
387,072 06 Dec 2015, 23:30:52 00000000000000000de64f000000000000000000000000000000000000000000
389,088 18 Dec 2015, 20:08:09 00000000000000000bc409000000000000000000000000000000000000000000
391,104 31 Dec 2015, 10:42:42 00000000000000000a9591000000000000000000000000000000000000000000
393,120 13 Jan 2016, 06:39:38 000000000000000009b31b000000000000000000000000000000000000000000
395,136 26 Jan 2016, 12:19:05 00000000000000000928f0000000000000000000000000000000000000000000
397,152 07 Feb 2016, 04:12:40 000000000000000007a114000000000000000000000000000000000000000000
399,168 19 Feb 2016, 12:34:16 000000000000000006b99f000000000000000000000000000000000000000000
401,184 04 Mar 2016, 23:25:56 000000000000000006f0a8000000000000000000000000000000000000000000
403,200 18 Mar 2016, 09:07:48 000000000000000006a4c3000000000000000000000000000000000000000000
405,216 01 Apr 2016, 06:34:35 00000000000000000696f4000000000000000000000000000000000000000000
407,232 14 Apr 2016, 08:25:41 000000000000000006274b000000000000000000000000000000000000000000
409,248 28 Apr 2016, 08:28:30 0000000000000000062776000000000000000000000000000000000000000000
411,264 11 May 2016, 05:34:26 000000000000000005a8fa000000000000000000000000000000000000000000
413,280 24 May 2016, 21:02:46 0000000000000000058436000000000000000000000000000000000000000000
415,296 08 Jun 2016, 02:41:58 0000000000000000059ba0000000000000000000000000000000000000000000
417,312 21 Jun 2016, 05:18:58 0000000000000000053fd6000000000000000000000000000000000000000000
419,328 04 Jul 2016, 23:16:01 00000000000000000526fd000000000000000000000000000000000000000000
421,344 18 Jul 2016, 23:22:42 0000000000000000052669000000000000000000000000000000000000000000
423,360 02 Aug 2016, 18:50:42 0000000000000000057228000000000000000000000000000000000000000000
425,376 15 Aug 2016, 18:59:14 0000000000000000050edc000000000000000000000000000000000000000000
427,392 29 Aug 2016, 14:11:01 000000000000000004fb08000000000000000000000000000000000000000000
429,408 12 Sep 2016, 06:39:07 000000000000000004de5e000000000000000000000000000000000000000000
431,424 25 Sep 2016, 09:16:55 0000000000000000048ed4000000000000000000000000000000000000000000
433,440 08 Oct 2016, 10:53:30 00000000000000000440c4000000000000000000000000000000000000000000
435,456 22 Oct 2016, 18:02:58 00000000000000000455d2000000000000000000000000000000000000000000
437,472 05 Nov 2016, 16:46:58 0000000000000000045174000000000000000000000000000000000000000000
439,488 18 Nov 2016, 08:30:15 000000000000000003e6d4000000000000000000000000000000000000000000
441,504 02 Dec 2016, 02:46:26 000000000000000003d589000000000000000000000000000000000000000000
443,520 15 Dec 2016, 01:28:33 0000000000000000038b85000000000000000000000000000000000000000000
445,536 28 Dec 2016, 17:40:55 00000000000000000375ff000000000000000000000000000000000000000000
447,552 10 Jan 2017, 22:40:52 0000000000000000034379000000000000000000000000000000000000000000
449,568 22 Jan 2017, 22:52:52 000000000000000002cc47000000000000000000000000000000000000000000
451,584 04 Feb 2017, 23:38:49 0000000000000000029ab9000000000000000000000000000000000000000000
453,600 18 Feb 2017, 09:38:26 0000000000000000027e93000000000000000000000000000000000000000000
455,616 03 Mar 2017, 19:04:46 00000000000000000262df000000000000000000000000000000000000000000
457,632 17 Mar 2017, 08:36:15 0000000000000000024fb1000000000000000000000000000000000000000000
459,648 30 Mar 2017, 16:39:08 000000000000000002335a000000000000000000000000000000000000000000
461,664 13 Apr 2017, 02:59:50 0000000000000000021c73000000000000000000000000000000000000000000
463,680 27 Apr 2017, 02:20:01 0000000000000000021b3e000000000000000000000000000000000000000000
465,696 10 May 2017, 03:40:48 000000000000000001f6a7000000000000000000000000000000000000000000
467,712 23 May 2017, 07:29:52 000000000000000001d854000000000000000000000000000000000000000000
469,728 04 Jun 2017, 14:35:07 0000000000000000019eaf000000000000000000000000000000000000000000
471,744 17 Jun 2017, 23:18:53 0000000000000000018b7e000000000000000000000000000000000000000000
473,760 02 Jul 2017, 00:47:17 0000000000000000018d30000000000000000000000000000000000000000000
475,776 14 Jul 2017, 08:45:42 0000000000000000015ddc000000000000000000000000000000000000000000
477,792 27 Jul 2017, 11:03:54 0000000000000000014735000000000000000000000000000000000000000000
479,808 09 Aug 2017, 12:36:50 00000000000000000130e0000000000000000000000000000000000000000000
481,824 24 Aug 2017, 01:57:37 0000000000000000013ce9000000000000000000000000000000000000000000
483,840 06 Sep 2017, 13:23:15 000000000000000001310b000000000000000000000000000000000000000000
485,856 18 Sep 2017, 06:31:16 000000000000000000ff18000000000000000000000000000000000000000000
487,872 02 Oct 2017, 00:27:46 000000000000000000fa73000000000000000000000000000000000000000000
489,888 15 Oct 2017, 04:05:02 000000000000000000eb30000000000000000000000000000000000000000000
491,904 26 Oct 2017, 16:52:42 000000000000000000c1bd000000000000000000000000000000000000000000
493,920 10 Nov 2017, 15:13:51 000000000000000000ce4b000000000000000000000000000000000000000000
495,936 24 Nov 2017, 19:53:16 000000000000000000d0f6000000000000000000000000000000000000000000
497,952 06 Dec 2017, 16:23:21 000000000000000000b0ed000000000000000000000000000000000000000000
499,968 18 Dec 2017, 13:55:20 0000000000000000009645000000000000000000000000000000000000000000
501,984 01 Jan 2018, 03:56:10 00000000000000000091c1000000000000000000000000000000000000000000
504,000 13 Jan 2018, 07:12:34 0000000000000000007e578c0000000000000000000000000000000000000000
506,016 25 Jan 2018, 06:48:20 0000000000000000006c21460000000000000000000000000000000000000000
508,032 06 Feb 2018, 23:08:07 00000000000000000061e9f80000000000000000000000000000000000000000
510,048 20 Feb 2018, 08:20:59 0000000000000000005d97dc0000000000000000000000000000000000000000
512,064 05 Mar 2018, 04:21:18 0000000000000000005589a30000000000000000000000000000000000000000
514,080 18 Mar 2018, 11:40:18 000000000000000000514a490000000000000000000000000000000000000000
516,096 01 Apr 2018, 07:05:57 000000000000000000502ab70000000000000000000000000000000000000000
518,112 14 Apr 2018, 02:28:52 00000000000000000049500d0000000000000000000000000000000000000000
520,128 27 Apr 2018, 11:24:13 00000000000000000045fb530000000000000000000000000000000000000000
522,144 11 May 2018, 01:54:15 00000000000000000043eca90000000000000000000000000000000000000000
524,160 24 May 2018, 13:20:53 000000000000000000415a490000000000000000000000000000000000000000
526,176 05 Jun 2018, 18:18:06 00000000000000000038f8410000000000000000000000000000000000000000
528,192 19 Jun 2018, 09:20:45 000000000000000000376f560000000000000000000000000000000000000000
530,208 02 Jul 2018, 15:34:21 000000000000000000347a280000000000000000000000000000000000000000
532,224 17 Jul 2018, 03:50:49 000000000000000000365a170000000000000000000000000000000000000000
534,240 29 Jul 2018, 08:19:31 0000000000000000002f4f7b0000000000000000000000000000000000000000
536,256 11 Aug 2018, 09:40:59 0000000000000000002c0da70000000000000000000000000000000000000000
538,272 24 Aug 2018, 16:50:31 00000000000000000029d72d0000000000000000000000000000000000000000
540,288 07 Sep 2018, 03:14:39 0000000000000000002819a10000000000000000000000000000000000000000
542,304 20 Sep 2018, 21:15:39 000000000000000000275a1f0000000000000000000000000000000000000000
544,320 04 Oct 2018, 07:49:22 00000000000000000025c1910000000000000000000000000000000000000000
546,336 18 Oct 2018, 20:37:47 000000000000000000272fbd0000000000000000000000000000000000000000
548,352 01 Nov 2018, 20:54:16 000000000000000000272d920000000000000000000000000000000000000000
550,368 16 Nov 2018, 23:51:24 0000000000000000002a4e2f0000000000000000000000000000000000000000
552,384 03 Dec 2018, 11:59:28 00000000000000000031d97c0000000000000000000000000000000000000000
554,400 18 Dec 2018, 23:32:45 000000000000000000371ef40000000000000000000000000000000000000000
556,416 31 Dec 2018, 17:20:09 0000000000000000003218a50000000000000000000000000000000000000000
558,432 14 Jan 2019, 02:19:54 0000000000000000002fd6330000000000000000000000000000000000000000
560,448 28 Jan 2019, 06:35:13 0000000000000000003068350000000000000000000000000000000000000000
562,464 10 Feb 2019, 16:59:41 0000000000000000002e6f880000000000000000000000000000000000000000
564,480 24 Feb 2019, 16:33:58 0000000000000000002e5b500000000000000000000000000000000000000000
566,496 10 Mar 2019, 16:45:04 0000000000000000002e61170000000000000000000000000000000000000000
568,512 24 Mar 2019, 00:24:53 0000000000000000002c1f6c0000000000000000000000000000000000000000
570,528 06 Apr 2019, 23:43:43 0000000000000000002c071d0000000000000000000000000000000000000000
572,544 21 Apr 2019, 01:54:28 0000000000000000002c4e110000000000000000000000000000000000000000
574,560 04 May 2019, 08:32:13 00000000000000000029ff380000000000000000000000000000000000000000
576,576 18 May 2019, 08:31:36 00000000000000000029fb450000000000000000000000000000000000000000
578,592 30 May 2019, 22:43:04 00000000000000000025bb760000000000000000000000000000000000000000
580,608 14 Jun 2019, 01:03:50 00000000000000000025fd030000000000000000000000000000000000000000
582,624 27 Jun 2019, 02:59:30 00000000000000000023792c0000000000000000000000000000000000000000
584,640 09 Jul 2019, 09:17:48 0000000000000000001f0d9b0000000000000000000000000000000000000000
586,656 23 Jul 2019, 11:22:17 0000000000000000001f3a080000000000000000000000000000000000000000
588,672 05 Aug 2019, 02:52:08 0000000000000000001c30390000000000000000000000000000000000000000
590,688 18 Aug 2019, 20:49:42 0000000000000000001ba3d10000000000000000000000000000000000000000
592,704 01 Sep 2019, 02:35:01 0000000000000000001a213e0000000000000000000000000000000000000000
594,720 13 Sep 2019, 19:06:31 00000000000000000017abf50000000000000000000000000000000000000000
596,736 26 Sep 2019, 20:33:21 000000000000000000160f240000000000000000000000000000000000000000
598,752 10 Oct 2019, 14:08:55 00000000000000000015a35c0000000000000000000000000000000000000000
600,768 23 Oct 2019, 21:42:53 000000000000000000148edf0000000000000000000000000000000000000000
602,784 07 Nov 2019, 23:30:36 0000000000000000001620d10000000000000000000000000000000000000000
604,800 21 Nov 2019, 17:08:52 00000000000000000015b23e0000000000000000000000000000000000000000
606,816 05 Dec 2019, 20:02:25 00000000000000000015dbd20000000000000000000000000000000000000000
608,832 19 Dec 2019, 18:17:01 00000000000000000015bcd00000000000000000000000000000000000000000
610,848 01 Jan 2020, 21:54:27 0000000000000000001465f20000000000000000000000000000000000000000
612,864 14 Jan 2020, 23:42:37 000000000000000000130c780000000000000000000000000000000000000000
614,880 28 Jan 2020, 08:44:03 0000000000000000001232ff0000000000000000000000000000000000000000
616,896 11 Feb 2020, 07:10:24 000000000000000000121ad40000000000000000000000000000000000000000
618,912 25 Feb 2020, 08:28:42 000000000000000000122cbc0000000000000000000000000000000000000000

2. How is the target calculated?

The target for the first block was set at:

00000000ffff0000000000000000000000000000000000000000000000000000

Block 0

This initial (and maximum) target value is hard-coded in to the source code of every bitcoin node.1 It was probably best-guess by Satoshi at what be a good starting point for a difficult-enough target that would result in a 10-minute interval between new blocks.

After every 2016 blocks, each node will look at the time between the last 2016 blocks and work out if they were being mined faster or slower than 10 minutes on average.

Each block contains a timestamp in its block header. This timestamp is in Unix time, which is the number of seconds since 01 January 1970.

If blocks during this period were being mined faster than every 10 minutes, the target will adjust downwards to make it more difficult to get below the target for the next period of blocks.

Conversely, if blocks were being mined slower than every 10 minutes, the target will adjust upwards to make is easier to get below the target for the next period of blocks.

As a result, each node regularly recalculates the target to enforce a 10-minute interval between new blocks, even as miners join and leave the network over time.

Try it! - Target Recalculator

See the code at the bottom of the page for a real example.

What causes blocks to be mined faster or slower than every 10 minutes?

Well, first of all, mining is unpredictable, so you never know when a miner is going to find the next block with a block hash below the current target.

Secondly (and most importantly), miners can join and leave the network at any time, which affects the likelihood of new blocks being mined within 10-minute periods. The more miners there are on the network, the more hashing there is taking place, and the more likely it is a new block will be mined in under 10 minutes.

3. Do all nodes share the same target?

Each node on the network operates independently, so there is no “single target value” being sent around the network.

However, because all nodes adopt the longest chain of blocks as their blockchain, they will each end up calculating the same target as everyone else, so effectively all nodes end up sharing the same current target.

For example, when you run bitcoin for the first time, your node will perform the initial block download and calculate the targets as it goes. And because you’re receiving the same blocks as everyone else, you will end up calculating the same current target too.

Furthermore, all nodes continually share the same view of the blockchain (as they will always adopt the longest available chain of blocks). Therefore, nodes will also continually calculate the same target value as each new block is mined.

As a result, despite the fact nodes calculate the target independently, they each share the same blockchain and calculate the same target value as each other.

Everyone does the same calculation with the same chain data, so they all get the same result at the same link in the chain. – Satoshi Nakamoto

4. Why does bitcoin use a target?

The target regulates the speed at which new blocks are added on to the blockchain.

This has two benefits:

i. It gives blocks time to propagate across the network.

It’s ideal to have miners working on extending the same chain of blocks as much as possible. For this to work, we need to allow time for new blocks to propagate across the network before the next block gets mined.

If blocks are being mined faster than they can be broadcast across the network, it will result in miners regularly building competing chains. Only one of these will become the longest, so some miners will end up wasting energy working to build on top of a competing chain only for it to be left behind due to a chain reorganisation.

Therefore, this time delay between blocks allows them to propagate the network so that more miners can adopt the longest available chain, which concentrates the network’s mining power on extending the same chain of blocks.

If broadcasts turn out to be slower in practice than expected, the target time between blocks may have to be increased to avoid wasting resources. We want blocks to usually propagate in much less time than it takes to generate them, otherwise nodes would spend too much time working on obsolete blocks. – Satoshi Nakamoto

ii. A consisent issuance of new bitcoins.

Bitcoin is a currency, so having a fixed rate of new bitcoins introduced in to the system provides stability.

Thanks to the target you can be confident that new bitcoins will be minted at a predictable rate for as long as the network is running.

Coins have to get initially distributed somehow, and a constant rate seems like the best formula. – Satoshi Nakamoto

5. Why 10 minutes between blocks?

I don’t think anyone knows why 10 minutes exactly was chosen, except for Satoshi.

My guess is that it seems like a long-enough time to allow blocks to propagate around the network (to minimize chain reorganisations), and short-enough so that you do not have to wait too long for a new transaction to get mined on to the blockchain. And 10 is a nice round number.

6. Where can you find the target?

The target gets stored in the bits field in the block header of every block.

The target is stored in a compact format to save space.

Commands

bitcoin-cli getblocktemplate

The is the simplest way to get the current target. When you request a block template for mining it also returns the current target:

$ bitcoin-cli getblocktemplate '{"rules": ["segwit"]}' | grep target
  "target": "000000000000000000122cbc0000000000000000000000000000000000000000",

bitcoin-cli getdifficulty

Similarly you can just ask for the current difficulty, which you can then convert to the target:

$ bitcoin-cli getdifficulty
15486913440293

bitcoin-cli getblockheader

Alternatively, as mentioned, the target at the time of mining is stored in every block header in the bits format (which you can convert to a full target value):

$ bitcoin-cli getblockheader 000000000000000002e9533a4fe03bb251b3fdb30ffaa384aad133b7fae594cf
{
  "hash": "000000000000000002e9533a4fe03bb251b3fdb30ffaa384aad133b7fae594cf",
  "confirmations": 207763,
  "height": 401184,
  "version": 4,
  "versionHex": "00000004",
  "merkleroot": "b4afa0502a55fdfa4a5cda6ea2bc546ba527d276ea9c7e848b8cd478cd9b6607",
  "time": 1457133956,
  "mediantime": 1457132303,
  "nonce": 3778923481,
  "bits": "1806f0a8",
  "difficulty": 158427203767.3917,
  "chainwork": "00000000000000000000000000000000000000000012da32364c8f47d519604d",
  "nTx": 845,
  "previousblockhash": "000000000000000003c4a4d9c62b3a7f4893afe14eef8a6a377229d23ad4b1ea",
  "nextblockhash": "00000000000000000037ab74c8db9b7a9d7de039210d8eafaeb44ba35adfb624"
}

Tip: You can get the target for the top block in the chain with: $ bitcoin-cli getblockheader $(bitcoin-cli getblockhash $(bitcoin-cli getblockcount))

Note: This will give you the target for that block, and not necessarily the current target being used for the next block.

Code

Here’s some example Ruby code for calculating new target values. This code works out the new target for block 403,200, using the timestamps from blocks 401,184 and 403,199.

# 403,200 - NEW TARGET
# 403,199              | last block
#                      |
#                      |
#                      |
# 401,184 - NEW TARGET | first block (target = 0x000000000000000006f0a8000000000000000000000000000000000000000000)

# 1. Get the timestamps for the first and last block in the target adjustment period
first = 1457133956 # block 401,184
last  = 1458291885 # block 403,199

# 2. Work out the ratio of the actual time against the expected time
actual = last - first     # 1157929 (number of seconds between first and last block)
expected = 2016 * 10 * 60 # 1209600 (number of seconds expected between 2016 blocks)
ratio = actual.to_f / expected.to_f

# 3. Limit the adjustment by a factor of 4 (to prevent massive changes from one target to the next)
ratio = 0.25 if ratio < 0.25
ratio = 4 if ratio > 4

# 4. Multiply the current target by this ratio to get the new target
current_target = 0x000000000000000006f0a8000000000000000000000000000000000000000000
new_target = (current_target * ratio)

# 5. Don't let the target go above the maximum target
max_target = 0x00000000ffff0000000000000000000000000000000000000000000000000000
new_target = max_target if new_target > max_target

# 5. Truncate the target, because the official target is the truncated "bits" format stored in the block header
# This code is a bit rough, because it's working with strings when I should really be working with actual bytes.
new_target = new_target.to_i.to_s(16) # convert from decimal to hexadecimal
new_target = new_target.size % 2 != 0 ? '0' + new_target : new_target # make sure it's an even number of characters (i.e. bytes)
truncated = new_target.scan(/../).each_with_index.map { |byte, i| byte = i >= 3 ? "00" : byte }.join # set all bytes apart from first 3 to zeros
# e.g. 6a4c316c01f354000000000000000000000000000000000 <- full precision
# e.g. 6a4c3000000000000000000000000000000000000000000 <- official target

# 6. Display the full target (with leading zeros)
target = truncated.rjust(64, '0')
puts target
# 000000000000000006a4c3000000000000000000000000000000000000000000

Tip: You can get the timestamp for a block with bitcoin-cli getblockheader <hash> (and you can get the block hash for a block at a specific height with bitcoin-cli getblockhash <height>).

Official Target: The official target is the truncated target that gets stored in the block header (in the bits field), so it’s not actually the full-precision target that you get after adjusting the previous one.

Off-by-one: You may notice that new target is calculated using the time across 2015 blocks (and not across 2016 as you would expect). This is an implementation error in the code that still exists today.

Factor of 4: Target adjustments are limited by a factor of 4 to prevent overly-large adjustments from one target to the next.

Thanks

  • Thanks to David Harding for pointing out that you can get the target directly from bitcoind with bitcoin-cli getblocktemplate.

  1. https://github.com/bitcoin/bitcoin/blob/master/src/chainparams.cpp#L106↩︎

By Greg Walker,

Last Updated: 25 Dec 2019
  • 25 Dec 2019: /guide/target - added tooltip to calculator
  • 24 Dec 2019: /guide/target - added target adjustment calculator
  • 22 Dec 2019: edit
  • 22 Dec 2019: edit
  • 20 Dec 2019: /guide/target - edits
  • 20 Dec 2019: moved old target page to /guide/archive
  • 20 Dec 2019: /guide/target - new page (first draft)
  • 11 Dec 2019: links to /guide/mining
  • 17 Oct 2019: longest chain (second draft, diagrams), resources page, router now includes config when running pages through PHP
  • 09 Oct 2019: renamed browser to explorer, glossary to guide, and guide to beginners

Hey there, it's Greg.

I'll let you know about cool website updates, or if something seriously interesting happens in bitcoin.


Don't worry, it doesn't happen very often.