Bitcoin halving: what it is and how it affects supply

What the bitcoin halving is

A bitcoin halving is the scheduled event that cuts in half the reward for adding a new block to the bitcoin blockchain. It happens every 210,000 blocks, which works out to roughly every four years, because blocks are designed to arrive about every ten minutes on average.

The reward miners receive for each block has two parts: newly created coins, called the block subsidy, and transaction fees. The halving affects only the subsidy. The schedule is built into the bitcoin software, so it is known in advance and no company or central bank controls it. For background on the coin itself, see what is bitcoin.

How halvings have reduced new supply

Bitcoin began in 2009 with a block subsidy of 50 bitcoin. The subsidy was halved to 25 in 2012, to 12.5 in 2016, to 6.25 in 2020, and to 3.125 in 2024. Each step slows the rate at which new bitcoin enter circulation.

Because the subsidy keeps halving, total supply approaches a hard cap of 21 million coins and stays just below it. A halving does not change that cap; it changes only how quickly coins are created on the way there.

What a halving means for miners and the market

For miners, a halving cuts the subsidy part of their income at once, so their revenue depends more on transaction fees and on the bitcoin price. Fees are covered in bitcoin transaction fees, and the mining process is compared with other methods in proof of work vs proof of stake. Miners with higher costs may stop mining, and the network's difficulty adjusts to the computing power that remains active.

Many people expect halvings to affect prices, but the evidence is mixed, and past patterns do not predict the future. Markets respond to many factors at once. Crypto prices are volatile, and you can lose money if you buy or sell bitcoin. This article does not give a view on prices.

Worked example: miner income after a halving

Suppose a block pays a subsidy of 10 coins plus 1 coin in fees. After a halving, the subsidy falls to 5 coins while the fees stay at 1, so the total per block drops from 11 coins to 6, a fall of about 45 percent. These numbers are hypothetical, and real subsidies and fees differ.

Frequently asked questions

How often does bitcoin halve?

Roughly every four years, after every 210,000 blocks. The exact timing depends on how fast blocks are actually found, so a halving can arrive earlier or later than the average. It is automatic under the protocol rules, so no one needs to vote or announce it.

Does the bitcoin halving make the price go up?

There is no guarantee. Price depends on demand, sentiment, regulation and many other factors, and the effect of past halvings is debated. A halving reduces new supply, which is one factor among many, but it does not promise a price rise. Crypto prices are volatile, and you can lose money.