21 million cap
Also · Fixed supply · Hard cap
Bitcoin’s supply is capped just under 21 million coins by its consensus rules. The cap exists because every node checks it, not because an institution promises it.
Bitcoin’s consensus rules fix how many new coins each block may create, and halve that amount every 210,000 blocks. Summed over time, the issuance converges on 21 million BTC, and in practice ends slightly below it because of rounding and early mistakes. Coins lost to forgotten keys shrink the usable supply further.
Nothing enforces this limit except verification. Every full node rejects a block that creates more than the rules allow. A majority of the economy could in theory adopt new rules, which is exactly why the cap is better described as a social fact guarded by code than as a law of nature.
In French · Plafond des 21 millions
