What is the maximum total supply of Bitcoin?

The maximum total supply of Bitcoin is 21 million coins, a limit enforced by the cryptocurrency’s issuance rules.

New bitcoins enter circulation as rewards for miners that add valid blocks to the blockchain. The original block reward was 50 bitcoins, but it is cut in half after every 210,000 blocks, an event known as a halving. This declining issuance schedule is designed to make new supply increasingly scarce over time.

The 21-million figure is commonly described as exact, but the protocol’s reward arithmetic results in a theoretical total slightly below 21 million: about 20,999,999.9769 bitcoins. In everyday explanations, “21 million” remains the correct and standard answer. Lost coins also reduce the amount that can actually be spent, but they do not change the protocol’s supply limit.

Another common mistake is confusing total supply with circulating supply. Circulating supply changes as mining continues and as coins are lost or recovered; the maximum supply is the long-term ceiling. The final scheduled issuance is generally expected around the year 2140, after which miners will rely mainly on transaction fees.