> ## Documentation Index
> Fetch the complete documentation index at: https://docs.erna.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# dayMultiplier

```ts theme={null}
function dayMultiplier(factor, opts?): RuleEntry<"day-cost-multiplier", object & CostRuleOptions>;
```

Multiplies the base rate for assignments on specified days.

## Parameters

<ResponseField name="factor" type="number" required />

<ResponseField name="opts">
  [`CostRuleOptions`](./CostRuleOptions)
</ResponseField>

## Returns

`RuleEntry`\<`"day-cost-multiplier"`, `object` & [`CostRuleOptions`](./CostRuleOptions)>

The base cost (1x) is already counted by [minimizeCost](minimizeCost);
this rule adds only the extra portion above 1x.