The halving is a built-in event that cuts the number of new bitcoin created per block in half. It happens every 210,000 blocks. With blocks arriving about every ten minutes, that is roughly every four years.
The schedule so far
In 2009 the block reward subsidy was 50 BTC. It fell to 25 on 28 November 2012 (block 210,000), to 12.5 on 9 July 2016 (block 420,000), to 6.25 on 11 May 2020 (block 630,000), and to 3.125 on 20 April 2024 (block 840,000). The next halving, at block 1,050,000 and expected around spring 2028, will cut it to 1.5625 BTC.
Why it exists
Halvings make the supply predictable and limited. Add up 210,000 × 50 + 210,000 × 25 + … and the series approaches 21 million. Because the subsidy is counted in whole satoshis, it eventually rounds down to zero. That will happen around the year 2140, when the last fractions of a bitcoin are mined. Just over 20.1 million coins existed as of October 2026.
Effects on miners
Overnight, a miner's income from new coins drops by half, while electricity bills stay the same. Less efficient operations may shut down. When that happens, the difficulty adjusts downward so blocks keep coming roughly every ten minutes. Over time, transaction fees are meant to replace the shrinking subsidy as the main reward for securing the network.
Effects on price?
Past halvings were followed by large price rises within a year or two. Many people credit the reduced flow of new supply. Others point out that a handful of cycles is a tiny sample, and that the halving date is known years in advance, so markets can price it in. Treat any "halving rally" claim as a hypothesis, not a law.
What is certain is the code itself: no one can print extra bitcoin, and the schedule can be checked by any full node.