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# UnitPower

A unit of measure for power.

```
class UnitPower
```

## Overview

You typically use instances of [`UnitPower`](/documentation/Foundation/UnitPower) to represent specific quantities of power using the [`NSMeasurement`](/documentation/Foundation/NSMeasurement) class.

### Power

Power is the amount of energy used over time. The SI unit for power is the watt (W), which is derived as one joule per second (1W = 1J / 1s).

The [`UnitPower`](/documentation/Foundation/UnitPower) class defines its [`baseUnit()`](/documentation/Foundation/Dimension/baseUnit()) as [`watts`](/documentation/Foundation/UnitPower/watts), and provides the following units, which are initialized using [`UnitConverterLinear`](/documentation/Foundation/UnitConverterLinear) converters with the specified coefficients:

|Name      |Method                                                                      |Symbol|Coefficient|
|----------|----------------------------------------------------------------------------|------|-----------|
|Terawatts |``doc://com.apple.foundation/documentation/Foundation/UnitPower/terawatts`` |TW    |`1e12`     |
|Gigawatts |``doc://com.apple.foundation/documentation/Foundation/UnitPower/gigawatts`` |GW    |`1e9`      |
|Megawatts |``doc://com.apple.foundation/documentation/Foundation/UnitPower/megawatts`` |MW    |`1000000.0`|
|Kilowatts |``doc://com.apple.foundation/documentation/Foundation/UnitPower/kilowatts`` |kW    |`1000.0`   |
|Watts     |``doc://com.apple.foundation/documentation/Foundation/UnitPower/watts``     |W     |`1`        |
|Milliwatts|``doc://com.apple.foundation/documentation/Foundation/UnitPower/milliwatts``|mW    |`0.001`    |
|Microwatts|``doc://com.apple.foundation/documentation/Foundation/UnitPower/microwatts``|µW    |`0.000001` |
|Nanowatts |``doc://com.apple.foundation/documentation/Foundation/UnitPower/nanowatts`` |nW    |`1e-9`     |
|Picowatts |``doc://com.apple.foundation/documentation/Foundation/UnitPower/picowatts`` |pW    |`1e-12`    |
|Femtowatts|``doc://com.apple.foundation/documentation/Foundation/UnitPower/femtowatts``|fW    |`1e-15`    |
|Horsepower|``doc://com.apple.foundation/documentation/Foundation/UnitPower/horsepower``|hp    |`745.7`    |

## Topics

### Accessing the Base Unit

[`+  baseUnit`](/documentation/Foundation/Dimension/baseUnit())

Returns the base unit.

### Accessing Predefined Units

[`terawatts`](/documentation/Foundation/UnitPower/terawatts)

The terawatts unit of power.

[`gigawatts`](/documentation/Foundation/UnitPower/gigawatts)

The gigawatts unit of power.

[`megawatts`](/documentation/Foundation/UnitPower/megawatts)

The megawatts unit of power.

[`kilowatts`](/documentation/Foundation/UnitPower/kilowatts)

The kilowatts unit of power.

[`watts`](/documentation/Foundation/UnitPower/watts)

The watts unit of power.

[`milliwatts`](/documentation/Foundation/UnitPower/milliwatts)

The milliwatts unit of power.

[`microwatts`](/documentation/Foundation/UnitPower/microwatts)

The microwatts unit of power.

[`nanowatts`](/documentation/Foundation/UnitPower/nanowatts)

The nanowatts unit of power.

[`picowatts`](/documentation/Foundation/UnitPower/picowatts)

The picowatts unit of power.

[`femtowatts`](/documentation/Foundation/UnitPower/femtowatts)

The femtowatts unit of power.

[`horsepower`](/documentation/Foundation/UnitPower/horsepower)

The horsepower unit of power.

## Relationships

### Conforms To

[`NSCoding`](/documentation/Foundation/NSCoding)

[`Hashable`](/documentation/Swift/Hashable)

[`Equatable`](/documentation/Swift/Equatable)

[`NSObjectProtocol`](/documentation/ObjectiveC/NSObjectProtocol)

[`CVarArg`](/documentation/Swift/CVarArg)

[`SendableMetatype`](/documentation/Swift/SendableMetatype)

[`CustomStringConvertible`](/documentation/Swift/CustomStringConvertible)

[`CustomDebugStringConvertible`](/documentation/Swift/CustomDebugStringConvertible)

[`NSSecureCoding`](/documentation/Foundation/NSSecureCoding)

[`Sendable`](/documentation/Swift/Sendable)

[`NSCopying`](/documentation/Foundation/NSCopying)

### Inherits From

[`Dimension`](/documentation/Foundation/Dimension)

---

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