What Is the Bitcoin Halving? Dates, History and What It Changes

Key takeaways

• The halving is a scheduled event in Bitcoin’s code that cuts the new bitcoin paid to miners per block in half, every 210,000 blocks.
• Four halvings have happened so far, in November 2012, July 2016, May 2020 and April 2024, and the reward is now 3.125 bitcoin per block.
• The halving is how the 21 million limit is enforced: each period creates half as many coins as the one before.
• It does not change the ten-minute block target or how mining difficulty works.
• What halvings do to price is debated, and nobody can say. This article makes no predictions.

What is the Bitcoin halving?

The Bitcoin halving is a pre-programmed event that cuts the reward miners earn for each new block in half. It occurs every 210,000 blocks. At about one block every ten minutes, that works out to roughly four years between halvings.

The rule is part of Bitcoin’s software and has been since the first release. Nobody schedules a halving or votes on it, and no company can delay it. Every node on the network knows the block height at which the reward drops, and a miner who claimed more than the allowed amount would have the block rejected. If you want the basics of how blocks and miners fit together, start with How Does Bitcoin Work?.

Why does the halving exist?

The halving exists to release new bitcoin gradually and to end issuance at a fixed total. When the network launched in 2009, each block created 50 new bitcoin. Instead of keeping that rate forever, the design halves it on a schedule, so each four-year period creates half as many coins as the last.

Those amounts add up to a limit. The first period of 210,000 blocks produced 10.5 million bitcoin, the next about 5.25 million, then about 2.625 million, and so on, with each step half of the previous one. The sum is just under 21 million. The last fractions will be issued around the year 2140, and What Is Bitcoin? explains why the limit is central to the project’s design.

Compare that with a currency whose supply is set by policy makers. Bitcoin’s supply path is known in advance and does not depend on anyone’s judgment, which is the main reason people describe it as predictable. Whether that is an advantage is a matter of opinion, covered in Why Does Bitcoin Have Value?.

The four halvings so far

Bitcoin has had four halvings. Each one is a fact on the public record, and block heights are exact, while the month is the one in which the block was found.

Halving	Block height	Month	Reward per block afterward
First	210,000	November 2012	25 bitcoin
Second	420,000	July 2016	12.5 bitcoin
Third	630,000	May 2020	6.25 bitcoin
Fourth	840,000	April 2024	3.125 bitcoin

Before the first, the reward was 50 bitcoin per block. By the fourth halving, roughly 94 percent of all the bitcoin that will ever exist had already been issued, which means most of the schedule has played out and the remaining halvings release progressively smaller amounts.

The fifth halving falls at block 1,050,000. If blocks continue to arrive at the ten-minute pace, that is expected around April 2028, though real block times vary and the date can move by days or weeks. For every halving, including projected ones, the Halving and supply explorer lets you enter a year or block height and see the reward and the amount issued by then. The table above is a summary, and the tool has the complete schedule.

What does a halving change for miners?

A halving cuts the new-coin part of a miner’s income in half overnight. Miners earn two things for each block: the subsidy, which is the newly issued bitcoin, and the transaction fees from the transactions in that block. At each halving, the subsidy falls by half while fees are unaffected.

That puts pressure on margins. A miner whose costs were manageable before may suddenly find that electricity and hardware eat most of the income. What happens next depends on several things at once, including the price of bitcoin at the time, the efficiency of the machines, the cost of power and how much fee income there is. Less efficient miners may switch off, and more efficient ones tend to keep going. Inside a Bitcoin Mining Operation goes through that economics in detail.

The longer-run point is that the subsidy keeps shrinking toward zero. Eventually miners will depend on fees alone. Whether those fees will be enough to keep the network secure is one of the real open questions about Bitcoin’s design, and the answer will only be known in the future.

What does the halving not change?

The halving changes the reward and nothing else in the protocol. Three common misunderstandings are worth clearing up.

Block time. The network aims for one block roughly every ten minutes. Difficulty adjusts about every 2,016 blocks to keep that pace as miners join or leave. When the reward halves, the target interval stays the same. Some slowdown can happen if miners switch off machines, but the difficulty adjustment corrects it.

The total cap. The halving does not alter the limit of just under 21 million. It is the mechanism that produces it.

Transactions and fees. Your ability to send bitcoin and the fee you pay depend on network demand and block space, not on the reward. See Bitcoin Fees Explained for how fees work.

Another point is that the halving is not a surprise. Its timing has been public since the software was released, and anyone can compute the future schedule. That is a very different thing from a one-off policy announcement.

Do halvings affect the price?

Nobody can say, and this site does not predict prices. The supply that miners add each day does fall at a halving, and people have argued about how that interacts with demand. But halvings are well known in advance, markets react to many things at once, and only four have happened. Four events, each surrounded by different conditions, are not enough to establish a rule.

If you hear a confident claim that a halving will lead to any particular price result, treat it as a sales pitch. Bitcoin is volatile, and decisions about money should be based on your own situation and advice from a qualified professional. The history of the earlier events is in The History of Bitcoin.

Frequently asked about the halving

Is it a “halving” of the price or of the coins people own? Neither. It halves only the new bitcoin issued to miners per block. Existing coins and balances are not touched.

Does the halving happen on a particular date? It is tied to a block number, not a calendar date. The block height is fixed, so the calendar date is an estimate until the block is actually found.

Can the halving be changed? Technically any rule can be changed if the network’s participants agree to adopt new software. In practice the schedule has stayed untouched since 2009, and changing the supply rules would be highly contentious.

New to all this? The Start Here path lists the core guides in order.

Where to go next

• Halving and supply explorer: the reward and supply for any year or block height.
• Inside a Bitcoin Mining Operation: how miners earn money and why the halving matters to them.
• Bitcoin Fees Explained: what miners are paid besides the subsidy.
• The History of Bitcoin: the milestones that surround each halving.
• How Many Bitcoin Are Left to Mine? The 21 Million Cap Explained: how the halvings add up to the cap.
• Bitcoin Hash Rate and Mining Difficulty Explained: the numbers that set the pace of mining.
• How Long Does It Take to Mine a Bitcoin?: why solo mining takes so long.