Bitcoin’s Lowest Block Hash Values

Abstract: In this short and simple piece, we take a look at a list of the lowest block hash values in Bitcoin history. We also compare the block hash values with the difficulty target and identify blocks where the block hash was lowest relative to the necessary target. The Bitcoin block mined on 15 June 2020, at height 634,842, has the lowest ever block hash value and is also the 2nd biggest “beat”, when compared to the difficulty target.

Overview

Bitcoin’s proof of work consensus mechanism consists of miners attempting to find a block hash, for each Bitcoin block, with a low enough value to be considered valid. The block hash value must be below the difficulty target. The difficulty target automatically adjusts every two weeks or so, to ensure the expected time one needs to wait for a Bitcoin block is around 10 minutes. The block hash value must be lower than the difficulty target value. In some cases it can be a little bit lower or in other cases it can be much lower, either way it does not really matter, the block is still valid.

Bitcoins lowest block hashes

Since Bitcoin launched, the price has appreciated and efficiency of mining machines has improved, therefore the block hash values have in general been getting lower and lower as time progresses and the required difficulty increases. The below table (Figure 1), lists the ten lowest block hash values in Bitcoin’s history. As one would expect, the blocks were all produced relatively recently, in the 2019 to 2021 period.

Figure 1 – Top 10 lowest Bitcoin block hashes

# Hash Height  Date Value
1 000000000000000000000003681c2df35533c9578fb6aace040b0dfe0d446413 634,842 15/06/2020 4.98 x1048
2 000000000000000000000019b43763eb4519f4fe65eae9be90fe73117b89026d 585,774 17/07/2019 3.76×1049
3 00000000000000000000001a9bf725a1f7d019440a04f39706c083751b62974d 675,600 21/03/2021 3.89×1049
4 00000000000000000000001e9590a06c8452a3ce553834b2bab3daebf62f8b79 658,771 26/11/2020 4.47×1049
5 0000000000000000000000250fae6b97e3241d86c65fb5be489875c49032b25b 679,468 16/04/2021 5.42×1049
6 00000000000000000000002d142973ed07a220bf571360b70b90f4f0a1e739ce 679,848 20/04/2021 6.59×1049
7 000000000000000000000030f8cf8e0a76db53525aff8d56dcfdf4c74fc7878c 625,857 14/04/2020 7.16×1049
8 000000000000000000000031a10e42c80137b3c3ad3e15c5dfb4ea213c83e497 622,050 18/03/2020 7.25×1049
9 000000000000000000000032ad53b18dadb72800d883f8e1188ceaa566b9a222 664,602 05/01/2021 7.41×1049
10 00000000000000000000003c5c9269d93153a4eb8fabef76318d849a2ec2b29e 696,345 18/08/2021 8.82×1049

Source: BitMEX Research

Note: Data up to block height 720,441

The block with the lowest ever block hash value was produced by Binance pool on 15 June 2020, at block height 634,842. The value of the block hash is 4.98 x1048 (approximately the number 5 followed by 48 zeros). The hexadecimal representation of this number, which is often shown in block explorers, has 23 leading zeros. As Figure 2 below indicated, at the time of writing, this is the only ever Bitcoin block with 23 leading zeros.

Figure 2 – Number of leading zeros in Bitcoin’s block hash

Number of leading zeros Count
8 47,419
9 20,178
10 17,377
11 20,715
12 21,694
13 93,292
14 36,098
15 23,966
16 53,307
17 115,939
18 119,830
19 140,545
20 9,455
21 593
22 32
23 1
Total 720,441

Source: BitMEX Research
Note: Data up to block height 720,441

Comparing the block hash value to the required difficulty target

Another interesting metric is comparing the block hash value with the required difficulty target value. In Figure 3 below, we have compared these two values in percentage terms. A valid block hash can in theory be between 0% to 100% lower than the required target difficulty. The block hash cannot be more than 100% lower than the target value, since the block hash value cannot be lower than zero. The table below lists the top 10 blocks in Bitcoin’s history, ranked by the percentage beat compared to the target difficulty (i.e. the ten closest blocks to 100%). These “lucky” blocks are relatively evenly distributed across Bitcoin’s history.

Figure 3 – Top 10 Bitcoin block hash percentage beats

# Hash Height  Date Beat
1 00000000000000000000013712632da34788a7b4ae2cd78f7982c7036610126b 368,527 05/08/2015 99.99991%
2 000000000000000000000003681c2df35533c9578fb6aace040b0dfe0d446413 634,842 15/06/2020 99.99975%
3 000000000000000000028c32e6952731326747bae4be8db0f832d6eea0362050 266,381 27/10/2013 99.99965%
4 00000000000000001e8d6829a8a21adc5d38d0a473b144b6765798e61f98bd1d 125,552 21/05/2011 99.99932%
5 00000000000000000000011246f099d94f91628d71c9d75ad2f9a06e2beb7e92 458,091 20/03/2017 99.99929%
6 000000000000000000000019b43763eb4519f4fe65eae9be90fe73117b89026d 585,774 17/07/2019 99.99874%
7 0000000000000000000466c0ab58135a577e310efe613e390bb21b72226aa677 274,352 11/12/2013 99.99858%
8 0000000000000000000000bb5b432a764ad6c7acf677dcd99161abfdf68e698e 500,174 19/12/2017 99.99810%
9 000000000000177131355902f9a7a9d94d1f57aba9ef4430bb01123190325977   61,068 15/06/2010 99.99757%
10 00000000000000000000053d3dfcc6d5bdf653567672b3e3771c54a36b0cd088 448,044 14/01/2017 99.99755%

Source: BitMEX Research

Note: Data up to block height 720,441

The largest beat occurred on 5 August 2015 at height 368,527. This block was mined by SlushPool and had a block hash value 99.99991% lower than the required target.

There is some overlap in Figure 1 and Figure 3, with the block at height 634,842 having the lowest ever block hash value in history and also being the 2nd biggest beat. The block at height 585,774 has the 2nd lowest ever block hash value, while also being the 6th largest beat.