The Bitcoin halving explained

What is the Bitcoin halving?

Every new Bitcoin block contains a special first transaction, the coinbase transaction, that pays the miner who found it. Part of that payment is brand-new bitcoin, called the block subsidy; the rest is transaction fees (see how Bitcoin mining works). The halving is the scheduled event at which the subsidy is cut in half.

There is no committee or vote involved. The rule lives in a short function in Bitcoin Core's source code called GetBlockSubsidy. It divides the current block height by 210,000 to count how many halvings have happened, starts from 50 bitcoin, and halves that amount once for each halving. A comment in the code notes that this happens approximately every four years. Every node runs the same check, so a miner that tries to pay itself more than the allowed subsidy plus fees produces a block that the rest of the network rejects.

How does the halving schedule work, block by block?

Bitcoin counts time in blocks. Its software targets one block every 10 minutes and re-tunes mining difficulty every 2,016 blocks to stay close to that pace. At exactly 10 minutes, 210,000 blocks would take 1,458 days, or just under four years — which is why halvings arrive roughly every four years, but never on a fixed date.

Each era lasts 210,000 blocks. Totals are cumulative bitcoin (M = million) with the share of 21 million in brackets, calculated from the code's schedule. Bitcoin Core's own reference data shows the chain had passed block 966,143 by September 2026, so four halvings have taken place and the fifth will come at block 1,050,000.

Why does the halving cap Bitcoin's supply near 21 million?

Each era issues half as many coins as the one before it: 10.5 million, then 5.25 million, then 2.625 million, and so on. A series that keeps halving like this approaches a limit — here, 21 million — without ever quite reaching it.

There is a further twist. Bitcoin Core counts amounts in satoshis, where one bitcoin equals 100,000,000 satoshis, and the halving is done by a whole-number shift that drops any fraction. Once the subsidy falls below one satoshi, it becomes zero. That happens after the 33rd halving, at block 6,930,000. At 10 minutes per block, that is roughly 132 years after Bitcoin launched in January 2009 — an estimate, not a date.

What does the halving change for miners and the network?

The halving cuts one of the two sources of miner revenue overnight. Transaction fees are unaffected. Over time, the Bitcoin whitepaper expected the incentive to shift: once the predetermined number of coins has entered circulation, it can transition entirely to transaction fees. The halving schedule is the slow path toward that point.

Mining difficulty does not change because of the halving itself. If some miners switch off because revenue no longer covers their costs, blocks slow down slightly, and the next 2,016-block adjustment lowers difficulty to bring the pace back toward 10 minutes. The network's security depends on enough honest computing power staying online, which is why the long-run balance between fees and subsidy is a recurring debate among Bitcoin developers and researchers.

Does the halving make Bitcoin's price go up?

This is the most common question, and the honest answer is that nobody can show it reliably. The halving is a known, scheduled change to new supply; it does not change demand, and the whole schedule has been public since 2009. Markets can price in information that is known in advance, so a predictable event may already be reflected in prices.

Research is mixed. A 2024 peer-reviewed study in the Journal of Risk and Financial Management looked at the 2012, 2016 and 2020 halvings, found that prices rose after each in the long run, but rejected its own hypotheses about when peaks and troughs would follow, and stressed that price depends on supply, demand, sentiment and market conditions. A 2025 working paper by Vladislav Virtonen, which tried to estimate the effect causally, found a statistically significant effect for 2024 but could not produce a robust estimate for 2020. Three or four events are a very small sample, and economists disagree on how much the halving explains.

What mistakes do beginners make about the halving?

• Thinking it happens on a fixed date. It happens at a block height. Calendar estimates move as block times vary.
• Believing existing coins are cut in half. Your balance does not change. Only the subsidy for new blocks is halved.
• Treating past price patterns as a forecast. A handful of halvings is too few to build a reliable rule, and studies disagree.
• Assuming exactly 21 million coins will exist. The code's schedule tops out just below that, and coins sent to lost keys still count in the total.
• Confusing the subsidy with miner revenue. Fees continue and may matter more over time.