[API reference](https://evolu.dev/docs/api-reference) › [@evolu/common](https://evolu.dev/docs/api-reference/common) › [local‑first/Evolu](https://evolu.dev/docs/api-reference/common/local-first/Evolu) › maxMutationSize

```ts
const maxMutationSize: PositiveInt;
```

Defined in: [packages/common/src/local-first/Evolu.ts:1015](https://github.com/evoluhq/evolu/blob/215bf32284e302f2fc68bdcc9df57cc7df5a6fc3/packages/common/src/local-first/Evolu.ts#L1015)

The largest [Mutation](https://evolu.dev/docs/api-reference/common/local-first/Schema/type-aliases/Mutation), in bytes.

A mutation's size is its change as encoded for sync: the table name, the ID,
and every column name and value, with a few bytes of overhead. A string takes
at most three bytes per UTF-16 code unit. Every mutation within the limit
fits one protocol message, so it can always sync. A larger mutation throws
and is not saved. Mutations of local-only tables are exempt, because they
never sync. Measure a mutation in advance with [Evolu.getMutationSize](https://evolu.dev/docs/api-reference/common/local-first/Evolu/interfaces/Evolu#getmutationsize).