What is a Bitcoin halving?
Understand the block-subsidy rule, why the date moves, and why a halving does not guarantee a price outcome.
The subsidy falls about every 210,000 blocks
The Bitcoin network awards a block subsidy to miners who produce valid blocks. At intervals defined by the protocol, that subsidy is cut in half. The interval is approximately 210,000 blocks.
Block height records a block’s place in the chain. The direct trigger for a halving is therefore a target block height, not a calendar appointment.
The target is block 1,050,000
The fourth halving occurred at block 840,000. One full 210,000-block cycle later, the next target is 1,050,000. Subtracting current height gives the remaining distance.
The subsidy and new issuance pace fall together
The block subsidy was 50 BTC before the first halving and is now 3.125 BTC. At the next target block it falls to 1.5625 BTC. A lower subsidy slows the creation of new bitcoin; it does not remove coins that already exist.
Block subsidy and cumulative issuance
Each halving cuts the block subsidy and new issuance pace in half while cumulative issuance approaches 21 million BTC.
↔ Scroll the chart horizontally to explore the full range.
- Block subsidy · log scale
- Cumulative issued share
The subsidy axis uses a log scale with one equal step per halving.
- Annual new issuance
- 164,250 BTC
- Simple annual rate at start
- 0.83%
- Cumulative issued share
- 93.75%
- Annual new issuance
- 82,125 BTC
- Simple annual rate at start
- 0.40%
- Cumulative issued share
- 96.88%
View chart data table
| Year | Post-halving subsidy | Annual new issuance | Simple annual rate at start | Cumulative issued share |
|---|---|---|---|---|
| 2012 | 25 BTC | 1,314,000 BTC | 12.51% | 50.0% |
| 2016 | 12.5 BTC | 657,000 BTC | 4.17% | 75.0% |
| 2020 | 6.25 BTC | 328,500 BTC | 1.79% | 87.5% |
| 2024 | 3.125 BTC | 164,250 BTC | 0.83% | 93.8% |
| 2028 | 1.5625 BTC | 82,125 BTC | 0.40% | 96.9% |
| 2032 | 0.78125 BTC | 41,062.5 BTC | 0.20% | 98.4% |
| 2036 | 0.390625 BTC | 20,531.25 BTC | 0.10% | 99.219% |
| 2040 | 0.1953125 BTC | 10,265.625 BTC | 0.05% | 99.609% |
| 2044 | 0.09765625 BTC | 5,132.8125 BTC | 0.02% | 99.805% |
| 2048 | 0.04882812 BTC | 2,566.406 BTC | 0.01% | 99.902% |
| 2052 | 0.02441406 BTC | 1,283.203 BTC | 0.01% | 99.951% |
| 2056 | 0.01220703 BTC | 641.6015 BTC | 0.00% | 99.976% |
| 2060 | 0.00610351 BTC | 320.8005 BTC | 0.00% | 99.988% |
Annual issuance and the simple annual rate are start-of-era references assuming ten-minute blocks and 52,560 blocks per year. Actual values vary with block production speed and cumulative issuance at the time.
Why does the date keep moving?
Explanations often use an average of ten minutes per block, but actual intervals vary. Faster and slower blocks change the estimated time at which the chain reaches its target.
The countdown combines current height with an average interval. It is not a time reserved by the network.
The main estimate uses ten minutes per block
BtcCal multiplies remaining blocks by 600 seconds and adds the result to the API response time. The browser then updates the main countdown locally every second.
Block and time progress can disagree
Block progress uses actual chain height. Time progress measures the calendar span from the fourth halving to the current estimated target. Differences are expected whenever block production departs from its long-run average.
Difficulty adjustment steers the average back toward ten minutes
Blocks are not produced at exact ten-minute intervals. Bitcoin reviews the pace of the previous 2,016-block period and adjusts mining difficulty for the next period so the long-run average stays near ten minutes per block.
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Period
Group 2,016 blocks
A block set representing roughly two weeks forms one adjustment period.
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Observe
Check the actual elapsed time
The network determines whether the previous period ran faster or slower than its target.
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Adjust
Change difficulty for the next period
Difficulty rises after a faster period and falls after a slower one.
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Target
Steer toward a ten-minute average
The mechanism shapes the long-run average, not the time of each individual block.
The countdown's two time references serve different roles
- Ten minutes per blockLong-run basis
- The main estimate applies the protocol's target interval to the blocks remaining.
- Last 2,016 blocksObserved reference
- The separate reference applies the recent observed pace to the same blocks remaining.
The recent pace is not a prediction that the same speed will continue after the next adjustment. BtcCal does not forecast the next difficulty value or future hashrate.
Miner revenue combines the subsidy and fees
A miner that produces a valid block can receive both the protocol-issued block subsidy and the transaction fees included in that block. A halving immediately cuts the subsidy component in half, but it does not determine mining profitability or the network hashrate on its own.
The subsidy keeps halving and is expected to become negligible around 2140. By then cumulative issuance approaches the 21 million BTC limit and transaction fees play a more important role in miner compensation. This does not guarantee future fee levels or mining returns.
What changes immediately
The new block subsidy is cut in half from the target block onward.
What affects profitability
BTC price, fees, electricity cost, hardware efficiency, and competing hashrate all matter.
How the network adjusts
Changes in mining pace feed into block intervals and the 2,016-block difficulty adjustment.
Supply rules and market price are separate
A halving reduces the rate of new issuance, but it does not guarantee a direction for market price. Demand, liquidity, and the wider economy are among the many other factors involved.
BtcCal's price-history chart places past observations beside halving events; it does not provide real-time trading signals or directional forecasts.
The next halving and its date calculation
2028 halving guide
See the target block, subsidy change, and current Season 5 data states.
View the next halving →Why the estimate changes
Read how actual block intervals and difficulty adjustments affect the estimated time.
Open the calculation guide →Question-based insights and guides
Browse every guide to the next schedule, historical prices, and data methods.
Open the insights hub →Content updated