Halving

The halving is written into Bitcoin's code. Every 210,000 blocks, which takes about four years at 10 minutes per block, the number of new bitcoin created with each block is cut in half. The reward started at 50 BTC in 2009, fell to 25 in November 2012, 12.5 in July 2016, 6.25 in May 2020, and 3.125 in April 2024. The next halving, expected around 2028, will bring it to 1.5625 BTC.

This schedule is what enforces the 21 million cap. Each halving reduces the inflow of new supply, and the series of halvings approaches zero around the year 2140. After the 2024 halving, new issuance fell to about 450 BTC per day, which puts Bitcoin's annual supply growth below 1 percent, lower than gold's.

Halvings have attracted attention because the three earlier ones were each followed by a major bull market within 12 to 18 months. Whether the halving causes those rallies or merely coincides with broader cycles is debated, and the effect of each successive halving on new supply is smaller in absolute terms. Miners feel the impact immediately, since their revenue per block drops by half overnight.