Glossary
Bitcoin halving
The Bitcoin halving is the automatic cut by half of the reward paid to miners for each new block. It happens every 210,000 blocks, roughly every four years, and slows the creation of new bitcoins until the 21 million cap.
Also called Halving, Halvening, Block reward halving, Bitcoin halvening
See also
The Bitcoin halving is a rule written into Bitcoin’s software: every 210,000 blocks, the number of new bitcoins paid to miners for each block is divided by two. With a new block about every ten minutes, that works out to roughly once every four years. The halving is how Bitcoin enforces its fixed supply of 21 million coins.
How the Bitcoin halving works
Miners who add a valid block receive two things: the transaction fees paid by users, and a block subsidy made of newly created bitcoins. The subsidy started at 50 BTC per block when the network launched in January 2009. Nobody votes on the cut: every node checks that a block does not pay itself more than the subsidy allowed at that height, and rejects it otherwise.
Past halvings and the next one
- 28 November 2012, block 210,000: 50 to 25 BTC
- 9 July 2016, block 420,000: 25 to 12.5 BTC
- 11 May 2020, block 630,000: 12.5 to 6.25 BTC
- 20 April 2024, block 840,000: 6.25 to 3.125 BTC
The next halving will happen at block 1,050,000, when the subsidy drops to 1.5625 BTC. It is expected in 2028; the exact day depends on how fast blocks are found, so countdown estimates move by a few days. Halvings continue until the subsidy reaches zero, around the year 2140.
A concrete example
Before April 2024, the network created about 900 BTC a day (144 blocks × 6.25 BTC). After the fourth halving, the same number of blocks produces about 450 BTC a day. A miner with the same machines and electricity bill earns half as many new coins, so fees and efficiency become more important for mining businesses.
Why it matters for users
The halving makes bitcoin issuance predictable: anyone can calculate how many coins will exist at any future date. It also matters for the security of the proof of work network, because the miner reward pays for that security.
Limits and misconceptions
A halving does not guarantee a price rise. Past halvings were followed by very different markets, and the event is known years in advance. In the long run, Bitcoin’s security will depend more and more on transaction fees, an open debate among developers and researchers. Our guide What is Bitcoin? covers the wider picture.