Halving
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A halving is a pre-programmed event in Bitcoin's protocol that cuts the block reward in half every 210,000 blocks (approximately every 4 years). It is the mechanism that enforces Bitcoin's fixed supply cap of 21 million BTC.
Other Proof of Work coins have similar mechanisms — Litecoin also halves, for example.
Bitcoin halving history
| Date | Block | Reward before | Reward after |
|---|---|---|---|
| Jan 2009 | 0 (genesis) | — | 50 BTC |
| Nov 2012 | 210,000 | 50 BTC | 25 BTC |
| Jul 2016 | 420,000 | 25 BTC | 12.5 BTC |
| May 2020 | 630,000 | 12.5 BTC | 6.25 BTC |
| Apr 2024 | 840,000 | 6.25 BTC | 3.125 BTC |
| ~2028 | 1,050,000 | 3.125 BTC | 1.5625 BTC |
Impact on miners
Each halving immediately cuts miner revenue per block by 50%. Miners with high electricity costs or older hardware may become unprofitable and shut down, which temporarily lowers network hashrate until difficulty adjusts downward.
Historically, Bitcoin's price has risen significantly in the months following each halving, partially offsetting the reward reduction.
When does Bitcoin run out of new coins?
The last Bitcoin will be mined around the year 2140. After that, miners will earn only from transaction fees.
