---
title: Primitive & Numeric Types
description: The boolean, numeric, and unit types of the Slint language.
SC: true
---

import SC from '@slint/common-files/src/components/SC.astro';
import SlintProperty from '@slint/common-files/src/components/SlintProperty.astro';
import Link from '@slint/common-files/src/components/Link.astro';
import NotInSC from '@slint/common-files/src/components/NotInSC.astro';

<SC>
## Primitive Types

### bool
<SlintProperty propName="bool" typeName="bool" defaultValue='false'>
boolean whose value can be either `true` or `false`.
</SlintProperty>

The default `bool` is `false`. \{#sls.type.bool}

## Numeric Types

</SC>

### angle
<SlintProperty propName="angle" typeName="angle" defaultValue='0deg'>
Angle measurement, corresponds to a literal like `90deg`, `1.2rad`, `0 25turn`
</SlintProperty>

### duration
<SlintProperty propName="duration" typeName="duration" defaultValue='0ms'>
Type for the duration of animations. A suffix like `ms` (millisecond) or `s` (second) is used to indicate the precision.
</SlintProperty>

### float
<SlintProperty propName="float" typeName="float" defaultValue='0'>
Signed, 32-bit floating point number. Numbers with a `%` suffix are automatically divided by 100, so for example `30%` is the same as `0.30`.
</SlintProperty>

`float` and `int` values have the following member functions:

#### to-fixed(digits: int) -> string

Returns a string representation of the number with `digits` digits after the decimal point.
It behaves like JavaScript's [`toFixed()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/toFixed).

#### to-precision(digits: int) -> string

Returns a string representation of the number with `digits` significant digits.
It behaves like JavaScript's [`toPrecision()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/toPrecision).

Both functions format the number using the decimal separator of the current locale.
See [Converting Between Numbers and Strings](../../language/type-conversions/#converting-between-numbers-and-strings).

```slint
export component FloatToString {
    property<float> pi: 3.14159;
    property<string> fixed: pi.to-fixed(2); // "3.14"
    property<string> precision: pi.to-precision(4); // "3.142"
}
```

In addition, call the <Link type="MathRef" label="math functions"/> in postfix style on any numeric value,
for example `(-10).abs()` or `x.round()`.

#### to-string-unlocalized() -> string

Returns a string representation of the number but not localized. This means the decimal separator will always be a dot.

<SC>

### int
<SlintProperty propName="int" typeName="int" defaultValue='0'>
Signed integral number.
</SlintProperty>

The default `int` is zero. \{#sls.type.int}

### length
<SlintProperty propName="length" typeName="length" defaultValue='0px'>
<NotInSC>
The type used for `x`, `y`, `width` and `height` coordinates. Corresponds to a literal like `1px`, `1pt`, `1in`, `1mm`, or `1cm`. It can be converted to and from length provided the binding is run in a context where there is an access to the device pixel ratio.
</NotInSC>
</SlintProperty>

A `length` is a distance.
The default `length` is zero. \{#sls.type.length}

</SC>

### percent
<SlintProperty propName="percent" typeName="percent" defaultValue='0%'>
Signed, 32-bit floating point number that is interpreted as percentage. Literal number assigned to properties of this type must have a `%` suffix.
</SlintProperty>

### physical-length
<SlintProperty propName="physical-length" typeName="physical-length" defaultValue='0phx'>
This is an amount of physical pixels. To convert from an integer to a length unit, one can simply multiply by `1px`. Or to convert from a length to a float, one can divide by `1phx`.
</SlintProperty>

### relative-font-size
<SlintProperty propName="relative-font-size" typeName="relative-font-size" defaultValue='0rem'>
Relative font size factor that is multiplied with the `Window.default-font-size` and can be converted to a `length`.
</SlintProperty>



Please see the language specific API references how these types are mapped to the APIs of the different programming languages.
