Bitcoin Halving Explained: What It Means for Miners and Supply
Roughly every four years, the reward Bitcoin miners receive for each new block is cut in half. This event — the halving — is written into Bitcoin's code and is the reason only 21 million bitcoin will ever exist. For miners, it is the single biggest scheduled change to their income.
How the halving works
Bitcoin's block subsidy halves every 210,000 blocks. With blocks arriving about every 10 minutes, that is approximately every four years. The subsidy started at 50 BTC per block in 2009.
| Halving | Approx. date | Block height | Subsidy after |
|---|---|---|---|
| — | Jan 2009 | 0 | 50 BTC |
| 1st | Nov 2012 | 210,000 | 25 BTC |
| 2nd | Jul 2016 | 420,000 | 12.5 BTC |
| 3rd | May 2020 | 630,000 | 6.25 BTC |
| 4th | Apr 2024 | 840,000 | 3.125 BTC |
| 5th | expected 2028 | 1,050,000 | 1.5625 BTC |
The subsidy keeps halving until it rounds down to zero, around the year 2140.
Run your own numbers with the free calculator: Bitcoin Mining Calculator
Open calculator →Why halvings exist
Halvings make Bitcoin's supply predictable and increasingly scarce. Over 19.9 million BTC have already been mined, and each halving slows the rate at which the rest are issued. After the 2024 halving, annual new supply fell below 1% of the total.
The impact on miners
On the day of a halving, every miner's subsidy income is cut in half overnight. Nothing else changes immediately — electricity costs stay the same.
Example: a machine earning $10 a day in subsidy revenue and paying $6 a day in electricity makes $4 a day. After a halving, with the same price and hashrate, it earns $5 from subsidy and loses about $1 a day.
What usually follows:
- Inefficient machines switch off, because they become unprofitable.
- Network hashrate may dip temporarily as those machines leave.
- Difficulty adjusts down if hashrate falls, which partly restores revenue for the remaining miners.
- Price and fees determine how quickly profitability recovers.
Transaction fees become more important
As the subsidy shrinks, transaction fees make up a larger share of miner revenue. During periods of very high network demand, fees have temporarily exceeded the subsidy. Bitcoin's long-term security model depends on fees eventually supporting miners on their own.
Does the halving move the price?
Earlier halvings were followed by strong bull markets, which is why halvings get so much attention. But the sample size is tiny, the supply cut is widely known in advance, and markets have changed a lot — including the arrival of spot ETFs in 2024. Treat any "halving pump" prediction with caution.
Planning for the next halving
If you are buying mining hardware, model profitability with the subsidy at 1.5625 BTC to see whether your machine will still be profitable after 2028. Change the block subsidy field in the Bitcoin mining calculator to test it.
CryptoMathly provides educational estimates only and is not financial, investment or tax advice. Crypto assets are volatile and you can lose money. Always verify figures with a qualified professional.