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

```ts
function fibonacci(
  initial: Duration,
): Schedule<
  number &
    Brand<"NonNaN"> &
    Brand<"Finite"> &
    Brand<"Int"> &
    Brand<"NonNegative"> &
    Brand<"LessThan281474976710655"> &
    Brand<"Millis">
>;
```

Defined in: [packages/common/src/Schedule.ts:381](https://github.com/evoluhq/evolu/blob/037c390af081e9944d616ff298a729515c5c5ab7/packages/common/src/Schedule.ts#L381)

Fibonacci backoff schedule.

Delays follow the Fibonacci sequence, growing more slowly than exponential:

- Step 1: `initial`
- Step 2: `initial`
- Step 3: `initial * 2`
- Step 4: `initial * 3`
- Step 5: `initial * 5`
- ...

Never stops — combine with [take](https://evolu.dev/docs/api-reference/common/Schedule/functions/take) or [maxElapsed](https://evolu.dev/docs/api-reference/common/Schedule/functions/maxElapsed) to limit.

### Fibonacci growth

```ts

// 100ms, 100ms, 200ms, 300ms, 500ms, ...
const step = fibonacci("100ms")(testCreateDeps());
assertOk(step(undefined), [100, 100]);
assertOk(step(undefined), [100, 100]);
assertOk(step(undefined), [200, 200]);
```