# Shortest and Longest block interval time ever recorded in Bitcoin

Bitcoin block interval time is on average 10 minutes, that is the difficulty is adjusted in such a way that every 10 minutes a miner will manage to find the right hash. This is just an average time though, the actual distribution for time confirmation is Poissonian.

What is the shortest and longest block interval ever recorded in Bitcoin?

(This data is current through block 535276.)

Based on block timestamps (which do not have to be accurate), the longest difference between successive blocks is 463160 seconds (5 days, 8 hours, 39 minutes, 20 seconds) between blocks 0 and 1. The second longest is 90532 seconds (1 day 1 hour 8 minutes 52 seconds) between blocks 15323 and 15324.

For "shortest", since timestamps are not strictly enforced and can be fudged accidentally or intentionally, it is possible for a block to have an earlier timestamp than its predecessor, by up to 2 hours (7200 seconds), in which case the time difference is negative. This has happened 13828 times. The most negative difference is −7125 seconds (1 hour 58 minutes 45 seconds) between blocks 156113 and 156114.

There have been 222 blocks with the same timestamp as their predecessor, giving a difference of 0.

The script I used to gather this data is at https://github.com/neldredge/bitcoin-blocks.

Actual block intervals are hard to know precisely, since we have no way of knowing for sure the actual time at which each block was mined. Some sites like blockchain.info record the first time at which their node received the block, but there is an unknown propagation delay between the time a block is actually mined and the time at which some other node receives it (though for a well connected node it is probably not much more than 1 second). It is also possible to receive blocks out of order, so the difference in receive times could also be negative. Moreover, such data is obviously not available for early blocks before the existence of the site in question.

In principle it could be possible to look for the longest and shortest difference between receive times, but I don't know how to retrieve that data in bulk.

• 3rd longest would also be interesting:) – tobi Feb 12 '19 at 16:06

the shortest is 0 seconds

the longest is 6 days (between #0 and #1)

• How can it be 0 seconds? This means a duplicate block with an hash collision. Two blocks can't have identical timestamps so they can't be mined at the same time, i.e. 0 seconds. ;) – user51260 Jul 31 '18 at 18:37
• the timestamp in block #N can be even less than in block #(N-1), because the time on computers in the world is not accurate. – amaclin Jul 31 '18 at 19:40
• By this reasoning surely the shortest block is minus one hour or so. – Pieter Wuille Jul 31 '18 at 19:51
• @Pieter, the `length` of interval can not be negative :) – amaclin Jul 31 '18 at 21:25
• @Cluster2k two blocks being found at the same time does not necessarily mean a hash collision. It is more likely the two blocks would have distinct hashes, but the same blockheight, found at pretty much the exact same moment. – chytrik Aug 1 '18 at 8:25

I'm not the author, but found this code:

Top 10 longest (using timestamp in block header, which can vary up to 2 hours from actual time)

1. Block 1: 2009-01-03 463160 seconds (5 days, ~8 hours)
2. Block 15324: 2009-05-22 90532 seconds (~25 hours)
3. Block 16564: 2009-06-05 90390 seconds (~25 hours)
4. Block 15: 2009-01-09 87157 seconds (~24 hours)
5. Block 16592: 2009-06-06 73782 seconds (~20 hours)

The shortest time between 2 blocks is impossible to give since the timestamp of a block is not that strict, since its not important to record the timestamp more accurately than to the second.

The reason for negative times between some blocks is not due to timestamps of blocks being "non strict" or whatever silly stuff above posters said. I can't give you the correct answer because its just been too long since I researched mining in great depth. It has to do with the way blockchains are verified and large pools having different chains at times (forks). Within 6 confirmations the longest chain will have been verified and overwrite any blocks recorded from a shorter chain.

None the less, the shortest time between 2 blocks is < 1s > 0s some odd number of milliseconds.