---
title: Booleans
introduction: >
  Booleans are the logical values `true` and `false`. In addition their literal
  forms, booleans are returned by [equality](../operators/equality) and
  [relational](../operators/relational) operators, as well as many built-in
  functions like [`comparable()`](../functions/map#comparable) and
  [`map-has-key()`](../functions/math#map-has-key).
---

<% example(autogen_css: false) do %>
  @debug 1px == 2px; // false
  @debug 1px == 1px; // true
  @debug 10px < 3px; // false
  @debug comparable(100px, 3in); // true
  ===
  @debug 1px == 2px  // false
  @debug 1px == 1px  // true
  @debug 10px < 3px  // false
  @debug comparable(100px, 3in)  // true
<% end %>

You can work with booleans using [boolean operators][]. The `and` operator
returns `true` if *both* sides are `true`, and the `or` operator returns `true`
if *either* side is `true`. The `not` operator returns the opposite of a single
boolean value.

[boolean operators]: ../operators/boolean

<% example do %>
  @debug true and true; // true
  @debug true and false; // false

  @debug true or false; // true
  @debug false or false; // false

  @debug not true; // false
  @debug not false; // true
  ===
  @debug true and true  // true
  @debug true and false  // false

  @debug true or false  // true
  @debug false or false  // false

  @debug not true  // false
  @debug not false  // true
<% end %>

## Using Booleans

You can use booleans to choose whether or not to do various things in Sass. The
[`@if` rule][] evaluates a block of styles if its argument is `true`:

[`@if` rule]: ../at-rules/control/if

<%= partial 'code-snippets/example-if' %>

The [`if()` function][] chooses returns one value if its argument is `true` and
another if its argument is `false`:

[`if()` function]: ../functions#if

<% example(autogen_css: false) do %>
  @debug if(true, 10px, 30px); // 10px
  @debug if(false, 10px, 30px); // 30px
  ===
  @debug if(true, 10px, 30px)  // 10px
  @debug if(false, 10px, 30px)  // 30px
<% end %>

<%= partial 'documentation/snippets/truthiness-and-falsiness' %>