Halving
Also: halvening
mining · beginner
Every 210,000 blocks (~four years), the new-bitcoin subsidy paid to miners is cut in half.
Bitcoin's issuance schedule is hard-coded. Every 210,000 blocks — roughly four years at ten-minute targets — the block subsidy (the new bitcoin a miner gets for finding a block) is cut in half. It started at 50 BTC per block in 2009, fell to 25 in 2012, 12.5 in 2016, 6.25 in 2020, and 3.125 in April 2024. Around 2140, the subsidy reaches zero and miners are paid entirely from transaction fees.
The halving is the mechanism that caps total supply at 21 million. It's a geometric series: 50 + 25 + 12.5 + ... summed over the halving schedule, multiplied by 210,000 blocks per epoch. The sum converges. There's no central decision needed; the curve is locked in by consensus rules every node enforces.
For mining economics, each halving is an instant 50% cut in revenue at unchanged price. The market typically prices in part of that ahead of time; the rest is absorbed by efficiency gains, fee revenue, or miner shutdowns. For monetary properties, halvings are the reason Bitcoin's inflation rate keeps dropping — currently under 1% per year and falling.