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.
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.