A block is 12.5 coins plus the fees for the coins sent inside that block.

Those fees are transaction fees.

The typical block is now 12.75 in size.  .25 which  are the transaction fees.

So if a 12.75 block is found a no fee pool such as antpool pays out 12.5 and keeps the .25 in transaction fees.

Which is really a fee of 2 % or so.


A pool that charges 1 % but shares the transaction fees would keep .1275 of a 12.75 block and pay out

12.625 of that block.

So be careful when you read what is really paid out.