ERC-721A explained
Quick answer
ERC-721A is an implementation of the ERC-721 NFT standard, created by Chiru Labs for Azuki, that makes minting several tokens in one transaction cost nearly the same gas as minting one.
ERC-721A is fully compatible with ERC-721 — wallets and marketplaces see an ordinary NFT — but it stores ownership differently to make batch mints cheap. That matters on any chain where collectors mint in multiples.
Who this is for
Collectors who wonder why multi-mints are cheap, and developers choosing a base contract.
How it saves gas
A standard ERC-721 writes an owner record for every token minted, so minting five tokens costs roughly five times the storage writes. ERC-721A writes the owner once for a consecutive batch and leaves the following slots empty; when someone asks who owns token 1,003, the contract scans back to the nearest written slot. Token IDs are sequential, which is what makes this possible.
Trade-offs
- The first transfer of a token inside a batch costs a little more gas, because ownership for that slot is written at that moment.
- Token IDs are sequential and assigned at mint; the contract cannot mint arbitrary IDs.
- Enumerating all tokens of an owner on-chain is expensive, so indexers (like Elevate's) do that off-chain.
How Elevate uses it
- Every collection contract is ERC-721A with OpenZeppelin access control, pausability and reentrancy protection layered on.
- Batch minting is why a phase's per-wallet limit can be, say, 50 without making a 50-token mint prohibitively expensive.
- The contract adds phases, signature allowlists, ERC-2981 royalties, transfer lock and reveal on top of the base standard.
Frequently asked questions
- Is ERC-721A a different token standard from ERC-721?
- No. It implements the ERC-721 interface, so anything that supports ERC-721 supports it. The difference is internal storage.
- Does ERC-721A make transfers more expensive?
- Only the first transfer of a token that was minted in a batch, and only slightly.
Sources
Written and maintained by the Elevate team. Last updated . Corrections: reach the team on the official Discord.
Related
- The Elevate collection contractOne ERC-721A contract per collection, with phases, royalties, transfer lock and reveal built in.
- ERC-2981 royalties explainedThe on-chain royalty standard, and how Elevate enforces it on marketplace sales.
- How to mint an NFT on Bittensor EVMThe ten user-facing steps from wallet setup to verifying your minted token.
Ready to mint? View verified Bittensor NFT collections.