At block 210,000, Bitcoin’s permitted subsidy changed from 50 BTC to 25 BTC. The block header records November 28, 2012. You can inspect the block record and independently compare it with the subsidy calculation.
The rule lives in block heights
For Bitcoin mainnet, the subsidy interval is 210,000 blocks. The calculation starts at 50 BTC and halves the amount at each interval, using integer units called satoshis. This schedule is explicit in the network parameters and validation code.
| Block height | Permitted subsidy |
|---|---|
| 0 | 50 BTC |
| 210,000 | 25 BTC |
| 420,000 | 12.5 BTC |
| 630,000 | 6.25 BTC |
| 840,000 | 3.125 BTC |
These are subsidies, not total block rewards. A miner can also collect transaction fees. The genesis block is a special case: its original subsidy is not spendable.
Why “every four years” is approximate
The network targets an average block interval of ten minutes. Individual intervals vary, so a fixed number of blocks does not correspond to an exact number of days. The first halving had a specific block trigger; it was not scheduled by a calendar. See the timing parameters.
What this tells us—and what it does not
The event demonstrates that the subsidy schedule was applied at the prescribed height. It does not establish a law connecting halvings with future prices. A supply rule alone does not determine demand or market value.
Explore the calculation yourself in our halving guide.