Bitcoin Halving, Explained: The Block Reward Gets Cut in Half
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Imagine a bakery whose oven releases a smaller batch after every 210,000 loaves. The calendar on the wall is only a rough guide; the counter on the oven decides when the change happens. Bitcoin's halving works a little like that, except the "loaves" are blocks and the scheduled cut applies to newly created bitcoin.
The 10-second version
- A halving cuts the block subsidy in half every 210,000 blocks. At an average pace near one block per ten minutes, that is roughly four years.
- The subsidy is not the whole miner reward. A miner can also collect transaction fees from the transactions included in its block.
- The latest halving was April 20, 2024, at block 840,000. The subsidy is now 3.125 BTC per block. At block 1,050,000, it is scheduled to become 1.5625 BTC. The calendar estimate is around 2028, not a guaranteed appointment.
Subsidy versus fees
When a miner produces a valid block, its special coinbase transaction may claim two things: the block subsidy, which creates new bitcoin under the protocol's rules, and the fees attached to transactions gathered into that block. Together, those are commonly called the block reward.
Think of the subsidy as a scheduled issuance allowance and fees as tips paid by people whose transactions are included. The subsidy shrinks on a known block schedule. Fees depend on actual transactions and the fee amounts users attach to them. They can vary from block to block. A busy block may offer more fee revenue than a quiet one, but there is no fixed tip amount.
This distinction matters because "the halving cuts the reward" is shorthand. It cuts the new-coin subsidy. It does not automatically halve transaction fees. The total income available to a miner can therefore change by a different amount, depending on fees and other conditions.
A schedule measured in blocks
Bitcoin began with a subsidy of 50 BTC per block. The first three halvings reduced it to 25 BTC at block 210,000, 12.5 BTC at block 420,000, and 6.25 BTC at block 630,000. The fourth took place on April 20, 2024, at block 840,000, reducing the subsidy to 3.125 BTC.
The next scheduled step is block 1,050,000. At that height, the subsidy will become 1.5625 BTC per block. That height is 210,000 blocks after the last halving. The protocol schedule is tied to block height; "around 2028" is a calendar estimate based on the pace blocks are found.
Why only an estimate? Bitcoin aims for an average block interval of about ten minutes, but blocks do not arrive on a clock. Some arrive close together; others take longer. Mining difficulty adjusts over time to keep the long-run average near its target, but the exact date for a future height cannot be known in advance. The block number is the rule. The year is a forecast.
What changes for miners?
At the halving block, the subsidy portion of a miner's possible revenue drops by half, measured in BTC. Fees remain separate. A miner's actual revenue also depends on which transactions fit in its block and the fee rates attached to them. Costs such as electricity, equipment, and financing are part of a miner's own business picture, not protocol rules.
That is a clear change in the reward formula. What it means for any particular miner is a practical question. Two operations can face the same subsidy and fee market but have different costs or operating choices. The halving alone does not tell us which miners will stay active, what fees will be later, or what a bitcoin will be worth.
Mining helps order and confirm transactions through proof of work. But a smaller subsidy does not let us announce a guaranteed security result in either direction. Future miner participation, fee demand, costs, and network conditions all matter. The schedule tells us how issuance changes; it does not provide a complete forecast of the network's future economics.
Sources
- Bitcoin.org: Bitcoin halving and history — read October 17, 2026.
- Bitcoin Core: mainnet consensus parameters — sets the 210,000-block halving interval and 600-second target spacing; read October 17, 2026.
- Bitcoin Developer Guide: Mining — describes miners' block reward and transaction-fee proceeds; read October 17, 2026.
- Bitcoin Developer Reference: Block Chain — explains the subsidy-plus-fees definition of block reward; read October 17, 2026.
The Developer Reference's example of 12.5 BTC is dated November 2017; it is used here only for the reward definition, not as a current subsidy figure.
This is a protocol explainer, not price, investment, legal, or tax advice. Spot a mistake? Tell us and we will fix it and say so here.