Swift For Any Measure: Simplified A clean, Swift interface for Foundation.Measurement

Read my post about it here.

Requirements: Swift 4.0+


The idea of type-safe numeric values, in other words, Measurements sounds great but, alas, the ergonomics are poor. At least until now. Wouldn't it be great to do this

    let m: Mass = 123(.kilograms) + 17(.stones)
    // or let m = Mass(123, .kilograms) + 17(.stones)
    m.converted(to: .pounds) // 509.1688786398349 lb

instead of this?

    let m = Measurement(value: 123, unit: UnitMass.kilograms)
    let m2 = m + Measurement(value: 17, unit: UnitMass.stones)
    print (m2.converted(to: .pounds)) // 509.1688786398349 lb

In addition to its verboseness, the Foundation Unit and Measurement APIs also lack the ability to dynamically declare compound units. This can make it difficult to perform dimensional analysis and other multi-step calculations.

The Ratio structure allows you to express the ratio between two units in a type-safe manner Multiplying a measurement with one unit type by a rate whose denominator is that same unit type causes those types to cancel out, resulting in a measurement with the numerator type.


For example, volume over time multiplied by time yields volume:

    // Ratio of Measures
    typealias FlowRate = Ratio<UnitVolume, UnitDuration>
    let rate: FlowRate = 84760(.cubicFeet, per: .seconds)
    let dailyFlow = (rate * 24(.hours)).converted(to: .megaliters)
    // -> ~ 207371ML


Swift Package Manager

Add the Rate package to your target dependencies in Package.swift:

import PackageDescription

let package = Package(
  name: "YourProject",
  dependencies: [
        url: "",
        from: "1.0.0"

Then run the swift build command to build your project.


License Information

MIT - See


Thanks to