A halving is a pre-programmed event in Bitcoin's code that cuts the reward miners receive for adding a new block by 50%. It happens roughly every four years, steadily slowing the rate at which new bitcoin is created until the 21-million cap is eventually reached.
The mechanism is what makes Bitcoin's supply predictable and disinflationary: issuance falls in regular, known steps rather than at a central bank's discretion. Each halving reduces the flow of new coins entering the market.
Halvings attract intense speculation about price, often framed as a supply shock. History offers only a handful of examples, though, and past price behaviour around them is not a reliable guide to the future. The supply schedule is certain; the market's reaction is not.
Worked example
The 2024 halving cut Bitcoin's block reward from 6.25 to 3.125 BTC, the fourth such step since 2009.
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This definition is general education, not investment advice. Markets — especially crypto — are volatile and you can lose money. Please read our disclaimer and see our methodology.