Glossary

Halving

The point, every 210,000 blocks or about four years, at which the new bitcoin each block creates is cut in half. The fourth, in April 2024, took it from 6.25 to 3.125 bitcoin per block; the fifth is expected around April 2028.

New bitcoin enter only one way: the miner who adds a block may pay itself a set amount of new coins, the block subsidy, along with the fees of the transactions in it. The subsidy started at 50 bitcoin in January 2009, and bitcoin’s software cuts it in half every 210,000 blocks. With a block about every 10 minutes, that comes to about four years.

The halving is fixed by block number, so no one decides when it happens, and no one can skip it: nodes reject any block that pays its miner more than the subsidy plus the fees.

What a halving changes is the new supply. The fourth, in April 2024 at block 840,000, cut it from about 900 bitcoin a day to about 450. What it doesn’t change is the cost of sending bitcoin, which depends on how many transactions are competing for room in blocks. That same day, as people rushed to create new tokens on bitcoin, block 840,000 paid its miner about 37.6 bitcoin in fees, twelve times its 3.125 new bitcoin, according to mempool.space.

After the 33rd halving, around 2140, the subsidy falls below one satoshi, which makes it zero, and miners will be paid by network fees alone. The guide on how many bitcoin will ever exist has the whole schedule, every halving so far and how many bitcoin have been created.

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