The halving is Bitcoin’s metronome: every 210,000 blocks the reward miners earn for each block is cut in half, slowly choking off new supply. This countdown tells you exactly how many blocks and roughly how many days stand between now and the next one, straight from the block height.
How it works
The reward era is the block height divided by 210,000, rounded down. The subsidy for an era is 50 BTC divided by two raised to the era number, using integer satoshi division to match consensus exactly. The next halving height is simply the start of the next era — one more than the current era, times 210,000. Subtracting the current height gives the blocks remaining.
To turn blocks into time, the tool multiplies the remaining blocks by Bitcoin’s ten-minute target interval and adds the result to today’s date. It then displays the current subsidy alongside the post-halving subsidy so you can see the supply cut at a glance, plus a table of the four halvings that have already happened.
Example and notes
At a height of 900,000 the network is in the fifth reward era with a 3.125 BTC subsidy; the next halving sits at block 1,050,000, and the tool counts the blocks and days down to it before the reward drops to 1.5625 BTC. Keep in mind the date is only as good as the ten-minute assumption — sustained hashrate growth shortens intervals and pulls the halving slightly earlier than a naive estimate.
Historical halvings and their block heights
| Halving | Block height | Subsidy before | Subsidy after | Approximate date |
|---|---|---|---|---|
| 1st | 210,000 | 50 BTC | 25 BTC | November 2012 |
| 2nd | 420,000 | 25 BTC | 12.5 BTC | July 2016 |
| 3rd | 630,000 | 12.5 BTC | 6.25 BTC | May 2020 |
| 4th | 840,000 | 6.25 BTC | 3.125 BTC | April 2024 |
| 5th | 1,050,000 | 3.125 BTC | 1.5625 BTC | approx. 2028 |
Why block intervals vary and what it means for the date estimate
Bitcoin’s difficulty adjustment — which runs every 2,016 blocks — keeps the average block time close to ten minutes by raising difficulty when blocks arrive faster and lowering it when they arrive slower. In practice, short-term intervals fluctuate widely around the ten-minute target depending on hashrate. The tool’s date estimate assumes exactly ten minutes per block, which is accurate on average over months but can be off by days or weeks for near-term halvings when hashrate is trending strongly in one direction.
A sustained increase in network hashrate over the months before a halving means blocks arrive faster than ten minutes on average, pulling the actual halving block slightly earlier than a pure block-count projection would suggest. Mining pool data and difficulty-history services provide more refined estimates when precision matters.
The subsidy schedule’s long-term supply effect
Bitcoin’s total supply is capped at approximately 21 million coins, a consequence of the halving schedule combined with integer arithmetic. Each halving cuts the daily new supply in half. After the 2024 halving, roughly 450 new bitcoins per day enter circulation (3.125 BTC × 144 blocks). After the next halving that drops to about 225 per day. By the mid-2030s, the new daily supply will be a fraction of a percent of the total circulating supply. After approximately the 33rd halving, the subsidy rounds to zero satoshis and miners will be compensated entirely through transaction fees.