About block 12,638
Bitcoin block 12,638 was mined by Unknown on April 29, 2009 at 12:57 PM UTC, 2 min 8 s after block 12,637. That is faster than the 10-minute average the network aims for: blocks come in bursts because finding one is pure chance.
It confirmed 1 transactions in 0.00 MB (0.0% of the 4 million weight-unit limit). The median transaction paid 0.00 sat/vB, and all fees added up to 0.0000 BTC. With the 50.000 BTC subsidy of halving era 1, Unknown earned 50.0000 BTC for this block.
Block 12,638 is number 543 of 2,016 in difficulty epoch 6; 1,473 blocks remain until the next difficulty adjustment at block 14,111. The next halving is at block 210,000, 197,362 blocks after this one.
Its hash starts with 8 zeros: that is the proof of work, a number below the target that the whole network’s hashrate had to search for. Unknown found 2 blocks in the week before. Today the block has 963,056 confirmations, so it is settled beyond any practical doubt.