Bitcoin halving: live countdown and the full schedule

Every 210,000 blocks, the number of new bitcoins a miner may pay itself for finding a block is cut in half. That event is the halving. It is written into the software every node runs, so its block height is known years in advance; only the calendar date moves, because blocks arrive at a variable pace. This page counts down to the next one with live data from the network, lists every halving so far, and explains what it does and does not change. It is educational only and is not advice to buy, sell or hold bitcoin.

What exactly is halved?

The first transaction in every block is the coinbase transaction. In it, the miner who found the block pays itself two things: the fees attached to the transactions it included, and a fixed amount of brand-new bitcoin called the block subsidy. The halving cuts only the subsidy. Fees are set by users bidding for block space and are not touched (see why a cheap Bitcoin fee can jump tenfold).

The rule is short. In Bitcoin Core, the function that sets the subsidy divides the block height by the halving interval to count how many halvings have happened, starts from 50 bitcoins, and shifts that amount right by the number of halvings — a binary way of dividing by two each time. The source comment reads: "Subsidy is cut in half every 210,000 blocks which will occur approximately every 4 years" (Bitcoin Core, validation.cpp). The interval itself, 210,000, is a consensus parameter for the main network (chainparams.cpp). A miner that pays itself more than the allowed subsidy plus fees produces an invalid block that the rest of the network rejects.

The original white paper describes the idea plainly: the first transaction in a block starts a new coin owned by its creator, which adds an incentive to support the network and distributes coins with no central issuer; once a set number of coins has entered circulation, the incentive can move entirely to transaction fees (Nakamoto, 2008, section 6).

Every halving so far

Block times below are the timestamps recorded in the blocks themselves, in UTC, as shown by the mempool.space explorer. A block's timestamp is set by its miner and can differ slightly from the wall clock.

The gaps between halvings were not exactly four years: about 3 years 11 months to the first, 3 years 7 months to the second, 3 years 10 months to the third and 3 years 11 months to the fourth. In each era, blocks came slightly faster than every ten minutes on average, because the hashrate kept rising faster than the difficulty could catch up.

Why the date keeps moving

The protocol targets one block every 600 seconds and checks its pace every 2,016 blocks (nPowTargetSpacing and nPowTargetTimespan). Between those checks, the pace drifts with the amount of computing power pointed at the network. When new machines switch on, blocks come a little faster until the next difficulty adjustment corrects it; when miners switch off, they come slower. Our difficulty adjustment tracker shows the current period's average.

That is why the panel above gives two estimates. One assumes exactly ten minutes per block from now on. The other uses the average block time of the current 2,016-block period. Neither is a promise. Over the hundreds of days left, a few seconds per block adds up to weeks. Any site that gives you the halving to the minute today is extrapolating, and its countdown will shift as the date approaches.

Where 21 million comes from

Add up the subsidies: 210,000 blocks at 50, then 210,000 at 25, then at 12.5, and so on. That is 210,000 × 50 × (1 + ½ + ¼ + …), and the bracket approaches 2, so the total approaches 21 million. In practice the total lands slightly below, because amounts are counted in whole satoshis (one hundred-millionth of a bitcoin) and each halving drops any fraction of a satoshi. The subsidy reaches 1 satoshi in the 33rd era and becomes zero at the 33rd halving, at block 6,930,000. Summed in satoshis, every subsidy ever paid comes to 2,099,999,997,690,000 satoshis: 20,999,999.9769 BTC.

At ten minutes a block, block 6,930,000 is roughly 132 years after the first block, so around the year 2140 — later or earlier depending on how fast blocks actually arrive. Fewer coins than this will ever be spendable: the 50 BTC in the genesis block cannot be spent, some early miners claimed less than they were allowed, and coins sent to lost keys stay where they are.

The halving in numbers

These figures follow from the schedule alone. They need no price or forecast.

How the last row is worked out: 164,250 ÷ 19,687,500 = 0.834%, and 82,125 ÷ 20,343,750 = 0.404%. After block 1,050,000, about 96.9% of all bitcoin that will ever exist will already have been created (20,343,750 ÷ 21,000,000). The remaining 656,250 coins will take more than a century to appear.

What it changes for miners

For a miner, the halving is a pay cut that arrives on a known block. Overnight, the subsidy part of every block's reward falls by half, while electricity bills, hosting contracts and machine loans stay the same. Fees soften the blow only if blocks are full and users are bidding up the price of space; when blocks are quiet, fees can be a small share of the reward. The live panel on our hashrate and hashprice page shows how much of the last 144 blocks' reward came from fees.

The miners hit hardest are those running older, less efficient machines or paying more for power. If their revenue falls below the cost of running, some switch off. When enough computing power leaves, blocks slow down, the next difficulty adjustment lowers the bar, and the remaining miners each earn a larger share. That loop — revenue falls, weak machines leave, difficulty falls, the rest earn more — is what keeps blocks near ten minutes through a halving. How large the effect is depends on the price of bitcoin, fees and power at the time, which nobody can know in advance.

You can try the arithmetic yourself with the mining revenue estimator on the hashrate page: put in a machine's hashrate and power use, then halve the subsidy in your head. A worked example there shows a machine that covers its electricity in era 4 and does not in era 5, with every other number unchanged.

Is the halving a price signal?

It is a supply event, known years ahead, and that is exactly why you should be careful with claims built on it. The new supply is cut in half on a schedule anyone can read; whether that matters for the price depends on demand, which is not on a schedule. Past halvings happened alongside very different conditions in interest rates, regulation, market structure and adoption, so the price paths after them are a handful of examples, not a law. The CFTC reminds investors that there is no such thing as a guaranteed investment or trading strategy and to be wary of anyone who promises one (CFTC: understand the risks of virtual currency trading).

If someone presents "the halving cycle" as a reason to buy now, ask how many examples the claim rests on (four), what else was happening each time, and what would prove it wrong. That is the same test we apply to the setups we post — see how we write trade ideas.

Questions people ask

When is the next Bitcoin halving?

At block 1,050,000. At ten minutes a block it falls in the first half of 2028; the live panel on this page gives the current estimate, which moves as the pace of blocks changes.

How many halvings are left?

After the fourth halving in April 2024, 29 more halvings will change the subsidy. The subsidy falls to 1 satoshi in the 33rd era and to zero at the 33rd halving, at block 6,930,000, around the year 2140.

What happens when all bitcoin has been mined?

Miners will be paid by transaction fees alone. The white paper anticipated this: once a set number of coins is in circulation, the incentive can transition entirely to fees. How large fees will be then depends on future demand for block space.

Does the halving change transaction fees?

No. The halving changes only the block subsidy. Fees are set by how much users bid for space in the next block, though miners may care more about fees once the subsidy is smaller.

Why is the total slightly less than 21 million?

Amounts are counted in whole satoshis, and each halving drops any fraction of a satoshi. The sum of every subsidy is 20,999,999.9769 BTC.

Sources

• Bitcoin Core source code, validation.cpp (GetBlockSubsidy) and kernel/chainparams.cpp (main network parameters).
• S. Nakamoto, Bitcoin: A Peer-to-Peer Electronic Cash System, 2008, section 6 "Incentive".
• Block heights and timestamps: mempool.space block explorer and API (live panel and the halving table).
• F. Velde, Bitcoin: A primer, Chicago Fed Letter No. 317, December 2013.
• CFTC, Understand the Risks of Virtual Currency Trading.

Risk warning. Educational content only, not financial or investment advice. Crypto assets are highly volatile and you can lose all the money you put in.

Keep reading

• Bitcoin difficulty adjustment: live tracker and how it works
• Bitcoin hashrate, hashprice and a mining revenue estimator
• Bitcoin network and mining glossary