Monad mainnet upgrade reduces storage read costs by up to 98%

Monad, an EVM‑compatible blockchain, activated its MonadTen revision on mainnet at 14:30 UTC on September 2. The MIP‑8 upgrade changes how the network charges contracts for reading storage, moving from slot‑by‑slot warming to grouping 128 consecutive slots into a single page.

How the new pricing works

The final MIP‑8 specification defines a storage page as 128 words of 32 bytes each (4,096 bytes). The first SLOAD on a page costs 8,100 gas. Subsequent reads within the same warmed page cost only 100 gas for the remainder of the transaction, unless a call frame reverts.

Measured impact on mainnet

In mainnet block 101672712, reading slot 0 incurred 8,100 gas, reading slot 1 on the same page cost 100 gas, and reading slot 128 (the first slot of the next page) again cost 8,100 gas. This demonstrates the step‑down from cold to warm reads within a page.

Implications for developers

Common Solidity storage layouts—sequential state variables, struct fields, and array elements—naturally benefit from the page‑level discount because they occupy consecutive slots. Mapping keys typically resolve to separate pages, but fields inside a struct stored under a mapping key remain contiguous and can share the discount.

Contracts that hardcode storage‑opcode gas costs may need adjustments, as the upgrade alters the underlying cost model while preserving EVM execution semantics.

Compatibility considerations

EIP‑2930 access‑list entries now warm entire pages, and proof formats must reflect the page model. Tooling that builds access lists, storage proofs, or gas estimates will need to account for the new page‑based warming mechanism.