The halving
Every 210,000 blocks, the new bitcoin paid to miners is cut in half. That is roughly every four years.
Miners who add a block to the chain earn newly created bitcoin, called the block subsidy, plus the fees in that block. The subsidy started at 50 BTC in 2009 and halves on a fixed schedule written into the code.
The schedule so far
- 2012, block 210,000: 25 BTC
- 2016, block 420,000: 12.5 BTC
- 2020, block 630,000: 6.25 BTC
- April 2024, block 840,000: 3.125 BTC
- Next, block 1,050,000 (expected around spring 2028): 1.5625 BTC
Because each halving cuts new supply, the total will never pass 21 million bitcoin. The last fraction is expected to be mined around the year 2140.