[API reference](https://evolu.dev/docs/api-reference) › [@evolu/common](https://evolu.dev/docs/api-reference/common) › [Time](https://evolu.dev/docs/api-reference/common/Time) › formatMillisAsDuration

```ts
function formatMillisAsDuration(
  millis: number &
    Brand<"Int"> &
    Brand<"NonNegative"> &
    Brand<"LessThan281474976710655"> &
    Brand<"Millis">,
): string;
```

Defined in: [packages/common/src/Time.ts:376](https://github.com/evoluhq/evolu/blob/e7144e2bbe9069362b62dec1b64a8aa922b8f1b0/packages/common/src/Time.ts#L376)

Formats [Millis](https://evolu.dev/docs/api-reference/common/Time/variables/Millis) as a human-readable duration string.

- Under 1 minute: `1.234s`
- Under 1 hour: `1m30.000s`
- 1 hour or more: `1h30m45.000s`

### Example

```ts
formatMillisAsDuration(1234 as Millis); // "1.234s"
formatMillisAsDuration(90000 as Millis); // "1m30.000s"
formatMillisAsDuration(3661000 as Millis); // "1h1m1.000s"
```