---
title: HKMetricPrefix
framework: healthkit
role: symbol
role_heading: Enumeration
path: healthkit/hkmetricprefix
---

# HKMetricPrefix

Prefixes that can be added to SI units to change the order of magnitude.

## Declaration

```swift
enum HKMetricPrefix
```

## Topics

### Prefixes

- [HKMetricPrefix.none](healthkit/hkmetricprefix/none.md)
- [HKMetricPrefix.femto](healthkit/hkmetricprefix/femto.md)
- [HKMetricPrefix.pico](healthkit/hkmetricprefix/pico.md)
- [HKMetricPrefix.nano](healthkit/hkmetricprefix/nano.md)
- [HKMetricPrefix.micro](healthkit/hkmetricprefix/micro.md)
- [HKMetricPrefix.milli](healthkit/hkmetricprefix/milli.md)
- [HKMetricPrefix.centi](healthkit/hkmetricprefix/centi.md)
- [HKMetricPrefix.deci](healthkit/hkmetricprefix/deci.md)
- [HKMetricPrefix.deca](healthkit/hkmetricprefix/deca.md)
- [HKMetricPrefix.hecto](healthkit/hkmetricprefix/hecto.md)
- [HKMetricPrefix.kilo](healthkit/hkmetricprefix/kilo.md)
- [HKMetricPrefix.mega](healthkit/hkmetricprefix/mega.md)
- [HKMetricPrefix.giga](healthkit/hkmetricprefix/giga.md)
- [HKMetricPrefix.tera](healthkit/hkmetricprefix/tera.md)

### Initializers

- [init(rawValue:)](healthkit/hkmetricprefix/init(rawvalue:).md)

## Relationships

### Conforms To

- [BitwiseCopyable](swift/bitwisecopyable.md)
- [Equatable](swift/equatable.md)
- [Hashable](swift/hashable.md)
- [RawRepresentable](swift/rawrepresentable.md)
- [Sendable](swift/sendable.md)
- [SendableMetatype](swift/sendablemetatype.md)

## See Also

### Units and quantities

- [Defining and converting units and quantities](healthkit/defining-and-converting-units-and-quantities.md)
- [HKQuantity](healthkit/hkquantity.md)
- [HKUnit](healthkit/hkunit.md)