Max Supply
The hard ceiling on how many units of a coin can ever exist, fixed by the protocol's rules.
Max supply is the absolute cap, the most units that will ever exist. Bitcoin's is famous: 21 million, written into the code, never to be raised without near-universal agreement. The last new bitcoin will be mined around the year 2140. That fixed scarcity sits at the heart of the 'digital gold' argument.
Not every coin has one. Ethereum has no fixed max supply; its issuance flexes, and burns can push net supply down or up. A hard cap signals predictable scarcity, which markets often reward. But the cap alone says little — what matters is how fast new coins arrive and how many are already out, not just the number at the very end.
Related terms
The number of coins actually available and trading in the market, excluding locked, reserved, or unreleased tokens.
Total SupplyEvery token that currently exists, including locked and reserved coins but excluding any that have been burned.
HalvingThe scheduled event that cuts the reward paid to bitcoin miners in half, tightening new supply.
BurnPermanently removing tokens from circulation by sending them to an address no one can spend from, shrinking supply.