Halving
A halving is a pre-programmed cut of the mining reward by half. In bitcoin it happens every 210,000 blocks, roughly once every four years, and halves the rate at which new coins appear.
How it works
The rule has been in bitcoin's code from the start: after every 210,000 blocks mined, the block reward is cut in half. It is not a decision or a vote but a condition that executes on its own.
That is what defines the whole issuance. The sum of every shrinking reward converges on 21 million coins, the last of which is mined around 2140. It is why bitcoin's supply is finite and known in advance.
For miners a halving cuts revenue for the same work in half. The weakest leave, difficulty drops, and those remaining earn more. Over time transaction fees rather than the block reward become miners' main income.
How the reward has changed
Bitcoin's reward per block, by year.
| 2009 | 50 BTC |
| 2012 | 25 BTC |
| 2016 | 12.5 BTC |
| 2020 | 6.25 BTC |
| 2024 | 3.125 BTC |
Blocks arrive roughly every ten minutes, about 144 a day. Since 2024 the network issues around 450 BTC a day where it issued 900 before.
What to keep in mind
- The date is known in advanceA halving is counted in blocks, so it is anticipated years out. It cannot arrive as breaking news.
- A price rise is not guaranteedPast halvings preceded rallies, but the sample is four events in fifteen years. That is not enough to call it a pattern.
- The network does not slow downDifficulty readjusts every two weeks, so blocks keep arriving every ten minutes regardless of miners leaving.
- Other networks work differentlyHalving is a rule of bitcoin and a few forks. Ethereum issues coins on a different model and has no halvings.