The zoom CSS descriptor sets the initial zoom factor of a document defined by the @viewport at-rule.

A zoom factor of 1.0 or 100% corresponds to no zooming. Larger values are zoomed in. Smaller values are zoomed out.

Related at-rule @viewport
Initial value auto
Percentages the zoom factor itself
Media as each of the properties of the shorthand:
Computed value auto, or a non-negative number or percentage as specified
Canonical order the unique non-ambiguous order defined by the formal grammar


/* Keyword value */
zoom: auto;

/* <number> values */
zoom: 0.8;
zoom: 2.0;

/* <percentage> values */
zoom: 150%;


The user agent will set the document's initial zoom factor. The user agent may use the size of canvas area on which the document is rendered to determine that factor.
A non-negative number used as the zoom factor.
A non-negative percentage value used as the zoom factor.

Formal syntax

auto | <number> | <percentage>


Specification Status Comment
CSS Device Adaptation
The definition of '"zoom" descriptor' in that specification.
Working Draft Initial specification

Browser compatibilityUpdate compatibility data on GitHub

Chrome Edge Firefox Internet Explorer Opera Safari
Basic support 29 ? No 10
Prefixed Requires the vendor prefix: -ms-
16 No
Android webview Chrome for Android Edge Mobile Firefox for Android Opera for Android iOS Safari Samsung Internet
Basic support 4.4 61 ? No 37 ? No

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