What is max supply?
- Author
- CRYPTO PORT Editorial
- Published
- Updated
- Reading time
- 4 min
In short
Max supply is the ceiling on how many tokens can ever exist — Bitcoin's 21 million is the standard example. Many tokens have no cap at all, so their supply keeps growing. Whether a cap exists is a matter of the contract or protocol rules, not of marketing copy.
Key points
- The ceiling on how many tokens can ever exist
- Many tokens are designed with no cap at all
- A cap only means something if the code enforces it
- Reaching the cap is a separate matter from price
Definition
The upper limit on how many units of a token can ever be issued, fixed by the protocol or contract so that issuing beyond it is not technically possible.
In Bitcoin, halving the block reward roughly every four years makes total issuance converge on 21 million. Rather than a single line stating the cap, the cap emerges from how the reward decays, and any issuance breaking node rules is rejected by the rest of the network.
ERC-20 tokens usually enforce a cap with a check inside the mint function that reverts if total supply would exceed it. If that check is in the code, the cap is real; if it only appears in the documentation, there is effectively no cap.
Uncapped designs are common too. Ethereum sets no issuance limit — new ether is issued as staking rewards while EIP-1559 burns part of each fee, so net change depends on usage. Having a cap is not better or worse, just a different design choice.
Watch out for
- · A stated cap and a cap enforced in the contract are two different things — check both
- · Having a cap does not put a floor under the price
- · In an upgradeable contract, the cap condition itself can be changed