What is a halving?

Bitcoin's protocol pays a reward — newly created bitcoin — to whichever miner successfully adds the next block to the chain. That reward is not fixed forever. Every 210,000 blocks, roughly every four years given Bitcoin's ~10-minute block time, the per-block reward is cut exactly in half.

It started at 50 BTC per block in 2009. Halvings have brought it down to 25, then 12.5, then 6.25, and most recently 3.125 BTC per block after the 2024 halving. The next halving, whenever it arrives, will cut that again to roughly 1.5625 BTC. This continues on a known schedule until the reward rounds down to zero, sometime around the year 2140.

Four halvings have occurred so far: November 2012, July 2016, May 2020, and April 2024. Each one cut the block subsidy in half again, exactly as scheduled. Stated neutrally, that is the entire historical fact — the schedule has executed as written every time, on block count rather than calendar date, which is why the exact day shifts slightly from one halving to the next depending on how quickly blocks were actually mined.

Commentary connecting past halvings to subsequent price moves is common, but a halving's only guaranteed effect is on the issuance rate itself. Any pattern observed after past halvings involved many other variables at the same time, and a sample of four events is not enough to establish that a halving causes a particular price outcome.

A halving is a supply-side event only. It reduces the rate at which new bitcoin is created; it says nothing on its own about demand. Price is a function of both supply and demand together, so a cut to new issuance does not by itself determine what price does next — that depends on how demand behaves independently, which the halving does not control.

Some market participants argue that, holding demand constant, less new supply reaching the market should put upward pressure on price — a "supply shock" argument. That is a stated hypothesis about incentives, not a mechanical guarantee, since demand rarely holds constant and the argument says nothing about timing or magnitude.

The more direct effect is on miner economics. When the block subsidy is cut in half, so is roughly half of a miner's revenue from that subsidy, and miners increasingly depend on transaction fees to make up the difference over time. Miners running less efficient hardware, or paying more for electricity, can be pushed into unprofitability and forced offline, which can pull down network hashrate in the short term until the network's difficulty adjustment recalibrates and remaining miners absorb the difference.