Bitcoin's fixed supply and predictable emission schedule
There will only ever be 21 million Bitcoin. This isn't a goal or a promise — it's mathematically enforced by the protocol. Every node verifies that new blocks don't create more Bitcoin than allowed.
Every 210,000 blocks (~4 years), the block reward is cut in half. This is called a halving. It's how Bitcoin controls its inflation rate and ensures the 21 million cap.
Imagine a gold mine where every 4 years, the amount of gold you can extract is cut in half. Early miners got the most, but the total amount of gold that will ever be extracted is fixed. Eventually, you're mining dust — but by then, the scarcity makes even dust valuable.
Block reward (BTC) by halving epoch
Unlike fiat currencies where central banks can print unlimited money, Bitcoin's supply schedule is known in advance for the next 120+ years. No surprises.
| Period | Annual Inflation |
|---|---|
| 2009-2012 | ~25%+ (rapid early growth) |
| 2012-2016 | ~9% |
| 2016-2020 | ~4% |
| 2020-2024 | ~1.8% |
| 2024-2028 | ~0.9% |
Every full node checks that each block follows the rules. If a miner tried to give themselves extra Bitcoin, their block would be rejected by every node on the network.
An estimated 3-4 million Bitcoin are lost forever (lost keys, early coins, Satoshi's coins, etc.). This means the effective supply is even lower than 21 million.