What is a Bitcoin halving?
A Bitcoin halving reduces the scheduled block subsidy; transaction fees are separate. It occurs every 210,000 blocks (roughly every four years). The first halving reduced the reward from 50 to 25 BTC; the next reduced it to 12.5, then 6.25, then 3.125 BTC. After the next halving it will drop to 1.5625 BTC. The issuance rate declines toward a total below 21 million BTC because subsidy amounts are rounded down to whole satoshis. A halving does not ensure a price increase.
How to use this countdown
- 1
View the countdown
The main timer shows days, hours, minutes, and seconds in an estimate based on the entered height and ten minutes per block.
- 2
Check block reward and supply
Inspect the scheduled subsidy and theoretical permitted issuance. Issuance includes genesis and does not deduct unclaimed, unspendable or lost coins.
- 3
Optional: override block height
You can enter a custom block height to simulate the countdown and metrics at a different point in time. Click Reset to request a new height snapshot.
Why use our Bitcoin halving countdown?
Ten-minute assumption
Based on current block height and 10-minute average block time, so you see the expected time until the next halving.
Supply and reward clarity
Compare theoretical permitted issuance and the next subsidy. These values are not measurements of circulating supply.
Sources: Bitcoin Core mainnet parameters and Esplora block-height API.
Frequently asked questions
Is the halving date exact?
No. The subsidy changes at a block height, not a scheduled calendar time. This timer assumes ten minutes per remaining block and ticks down from that estimate. Actual block intervals vary; a timer reaching zero does not confirm a halving.
Where does the block height come from?
The page requests the last block height from the public Blockstream Esplora endpoint on load and when you press Refresh. It does not continuously synchronize the chain. If the request fails, enter a verified height or retry; no time-derived height is substituted.
Does block reward include transaction fees?
The displayed value is only the scheduled block subsidy. Miner transaction fees are separate and are not halved by this calculation.
Is theoretical issuance the circulating supply?
No. It sums permitted subsidies through the entered block height, including genesis, with whole-satoshi rounding. It does not deduct unclaimed rewards, unspendable coins or lost coins, and it does not add fees. It is not a live supply audit.
What heights can I enter?
Use a whole nonnegative height up to 6,929,999. The next boundary after that range ends the subsidy. Invalid entries remain visible for correction rather than being silently clamped.