# Date.diff

## Function

Returns the difference between two dates, converted in the specified units.

## Syntax

```bt
date_value.diff(other, unit)
```

## Parameters

| Parameters | Type | Required | Default value | Description |
| ------ | ------ | ------ | ------ | ------ |
| other | Date/String/Number | Yes | None | Another date. |
| unit | String | No | millis | Difference unit. |

## Return value

| Type | Description |
| ------ | ------ |
| Int | The difference between the current date and other. |

## Code Example

```bt
start = date('2026-01-01 00:00:00')
end = start.add(2, 'days')
result = end.diff(start, 'days')

// Output: 2
print result
```

## Notes

- Supported units: millis, seconds, minutes, hours, days, weeks.