Swift FractionFormatter, like NumberFormatter, but outputs fractions.


A subclass of Apple's NumberFormatter that outputs pretty printed Unicode fractions rather than decimals.

Adding FractionFormatter to your project

In Xcode, use the File:Swift Packages:Add Package Dependency… menu command and enter


FractionFormatter is a direct replacement for NumberFormatter and is used the same way:

let fractionFormatter = FractionFormatter()
fractionFormatter.string(from: NSNumber(value: 0.5)) // "½"
fractionFormatter.string(from: NSNumber(value: 0.123)) // "¹²³⁄₁₀₀₀"

There are of course some connivance methods that make working with strings containing fractions easier:

fractionFormatter.double(from: "1 ½") // 1.5
fractionFormatter.double(from: "1 1/2") // 1.5
fractionFormatter.string(from: "1 1/2") // "1 ½"
fractionFormatter.string(from: "1 ½", as .Shilling) // 1 1/2

Filing feature requests and issues

The source is hosted on GitLab and mirrored on GitHub. If you find an issues or have a feature request, you can file it [here[(]

Known Issues

Radar FB7644708 - Pluralization and number formatting

When combined with Apple's MeasurementFormatter there are issues with pluralization. For example, using NumberFormatter to format fractional feet, it will output "0.5 feet", read as "zero point five feet", but if you substitute FractionFormatter then the output is "½ feet", which is not how it is normally written in English. Normally we say "half a foot", or more formally "one half of a foot" and thus write the singular form.

The workaround it to pull the symbol from the measurement and substitute the pluralized symbol when the measurement is between -1 and 1.


  • Swift Tools 5.0.0
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Last updated: Fri Sep 29 2023 08:06:16 GMT-0900 (Hawaii-Aleutian Daylight Time)