---
title: "wattUnit(with:)"
framework: healthkit
role: symbol
role_heading: Type Method
path: "healthkit/hkunit/wattunit(with:)"
---

# wattUnit(with:)

Returns a HealthKit unit for measuring power, using watt units with the provided prefix.

## Declaration

```swift
class func wattUnit(with prefix: HKMetricPrefix) -> Self
```

## Parameters

- `prefix`: A valid metric prefix value. For the complete list of prefix values, see doc://com.apple.healthkit/documentation/HealthKit/HKMetricPrefix.

## See Also

### Constructing power units

- [watt()](healthkit/hkunit/watt().md)