Bitcoin Halving

Bitcoin halving is the scheduled 50% cut in the number of new bitcoins created with each block. It happens every 210,000 blocks, which works out to roughly every four years. The cut applies to the block subsidy, the newly issued coins a miner receives for adding a valid block to the chain. Transaction fees are not halved. Because the subsidy is the only way new bitcoin enters circulation, each halving slows the growth of supply. That slowdown is why the event is often linked to scarcity and price.

The schedule is written into Bitcoin’s consensus rules from the original software released by Satoshi Nakamoto in 2009. No company, foundation or central bank decides when a halving happens. It triggers automatically when the chain reaches the next multiple of 210,000 blocks.

How Bitcoin halving works

Mining and the block reward

Bitcoin transactions are grouped into blocks and added to the blockchain through mining. Miners run specialized hardware that repeatedly hashes candidate blocks, searching for a result below a target set by the network. The first miner to find a valid block broadcasts it. Other nodes verify it and add it to their copy of the chain, and the race for the next block begins.

The winning miner collects the block reward, which has two parts:

1. Block subsidy: newly created bitcoin, fixed by the protocol for each block height. This is the part a halving cuts.
2. Transaction fees: amounts paid by users whose transactions are included in the block. Fees are set by demand for block space and are not affected by the halving schedule.

Why every four years

The protocol targets one block about every 10 minutes. Every 2,016 blocks (about two weeks), the network adjusts mining difficulty so that block times move back toward that target, whether hash rate has risen or fallen. At roughly 144 blocks per day, 210,000 blocks take about 1,458 days, or close to four years.

Because block times drift around the 10-minute target, halvings do not land on fixed anniversaries. The gap between the 2016 and 2020 halvings, for example, was shorter than the gap between 2012 and 2016. Any “next halving date” is a projection from the current block height and average block time.

The formula

The subsidy at any block height can be written as:

Subsidy = 50 BTC ÷ 2^(number of halvings so far)

where the number of halvings so far is the block height divided by 210,000, rounded down. At block 839,999 the result is 50 ÷ 2³ = 6.25 BTC. At block 840,000 it becomes 50 ÷ 2⁴ = 3.125 BTC.

The software stores amounts in satoshis (1 BTC = 100,000,000 satoshis), the smallest unit of bitcoin. Each halving divides the subsidy in satoshis and drops any remainder. Eventually the subsidy rounds down to zero.

Bitcoin halving dates and block rewards

Bitcoin coin supply per halving

Each 210,000-block period, often called a halving epoch or era, issues half as many coins as the one before it:

• Era 1 (50 BTC per block): 10.5 million BTC
• Era 2 (25 BTC): 5.25 million BTC
• Era 3 (12.5 BTC): 2.625 million BTC
• Era 4 (6.25 BTC): 1.3125 million BTC
• Era 5 (3.125 BTC, current): 656,250 BTC

Added together, this geometric series approaches 21 million. Because of satoshi rounding, the true cap is slightly below that figure. The first era alone produced half of all bitcoin that will ever exist. By May 2024, roughly 19.7 million BTC had been issued, leaving about 1.3 million to be mined over more than a century.

How many halvings are left

The subsidy reaches zero after 33 halving steps in total. With four completed by 2024, 29 remain. The subsidy is expected to fall to a single satoshi around 2136, and the last satoshi of subsidy is expected to be issued around 2140. After that, miners would be paid by transaction fees alone.

Worked example: what a halving does to issuance and miner revenue

Network issuance. At about 144 blocks per day:

• Before April 2024: 144 × 6.25 = 900 BTC of new supply per day
• After April 2024: 144 × 3.125 = 450 BTC per day

The daily flow of new coins halved overnight, while the existing stock of about 19.7 million BTC stayed the same. Supply growth slowed sharply, but supply did not shrink.

Hypothetical miner. Assume a mining operation controls 1% of total network hash rate and keeps that share. Assume also that transaction fees average 0.25 BTC per block and stay constant.

• Expected blocks per day: 144 × 1% = 1.44
• Before the halving: 1.44 × (6.25 + 0.25) = 9.36 BTC per day
• After the halving: 1.44 × (3.125 + 0.25) = 4.86 BTC per day

Revenue in bitcoin terms fell by about 48%, not 50%, because fees were not cut. The miner’s costs (electricity, hardware, cooling, staff) are mostly paid in dollars and do not change at the halving. To keep the same dollar revenue, the bitcoin price would need to rise by roughly 93% under these assumptions, or fees would need to rise, or the miner’s costs would need to fall.

How the halving affects mining

A halving is the largest single change in miner economics that the protocol schedules. Operators whose costs were close to their revenue before the event can become unprofitable at the next block. Their typical responses are to switch off older, less efficient machines, move to cheaper power, or exit.

If enough hash rate leaves, blocks arrive more slowly until the next difficulty adjustment lowers difficulty. Remaining miners then find blocks more easily. This feedback loop is how the network absorbs the revenue shock without stopping.

Scale matters. Large industrial miners can raise capital, buy newer hardware and negotiate power contracts ahead of a halving. Smaller miners and individual participants in mining pools see their payouts cut in the same proportion and have fewer ways to offset it. Each halving therefore raises the efficiency bar for staying in business and can push the industry toward larger operators.

Over the long run, the security budget (what the network pays miners to secure it) shifts from subsidy toward fees. Whether fees alone will support adequate security once the subsidy becomes negligible is an open question that the halving schedule leaves to future fee markets.

Halving and price impact

The supply argument is straightforward. If demand stays the same and the flow of new coins falls, fewer coins are available for sale each day, and miners, who often sell to cover costs, have less to sell. That combination can put upward pressure on price.

The record matches the argument loosely. Bitcoin’s price rose substantially in the months after the 2012, 2016 and 2020 halvings, and those gains built over months to more than a year rather than appearing on halving day. Several cautions apply:

• Small sample. Four halvings are not enough to establish a reliable pattern.
• Known in advance. The schedule is public years ahead. Markets can price in some or all of the supply cut before it happens.
• Shrinking effect on supply growth. Each halving removes fewer new coins in absolute terms. The 2012 cut reduced daily issuance by 3,600 BTC. The 2024 cut reduced it by 450 BTC.
• Other drivers. Each cycle overlapped with other forces, such as interest rate changes, new exchanges and products, and regulatory events. The 2024 halving, for example, came a few months after U.S. spot bitcoin ETFs received SEC approval, which makes it hard to isolate the halving’s effect.

Supply-based valuation models, such as stock-to-flow, treat halvings as the main price driver. These models are contested, and a model that fits past cycles gives no assurance that future cycles will behave the same way.

Halving, inflation and everyday users

Bitcoin’s issuance rate is its monetary inflation: the percentage by which supply grows each year. Each halving roughly halves that rate, which is why supporters describe bitcoin as increasingly scarce over time. This is different from consumer price inflation, which measures how much a currency buys. A low issuance rate does not stabilize the purchasing power of coins already in a wallet. Anyone who converts BTC to dollars gets that day’s market price, and whether a holder outpaces inflation depends on price, not on the issuance schedule.

What halving is often confused with

• Difficulty adjustment. Every 2,016 blocks, the network retunes how hard it is to find a block. A halving changes how much new bitcoin a block pays. The two interact but are separate rules.
• Stock split. A split divides existing shares and leaves each holder’s stake unchanged in value. A halving does not touch existing coins or balances. It only changes future issuance.
• Burning. Some tokens remove coins from circulation by sending them to unusable addresses. A halving destroys nothing.
• Halvings on other networks. Some other cryptocurrencies copied the mechanism with their own intervals (Litecoin halves every 840,000 blocks, for example). Their dates and rewards are separate from bitcoin’s.
• “Halvening.” This is an informal name for the same event, not a different one.

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