CWS Kit

Firefox Add-on Image Sizes — 2026

Every image dimension and text limit for publishing a Firefox add-on on addons.mozilla.org.

Icons

Firefox add-on icons can be PNG or SVG. SVG is preferred for scalability, but PNG is more widely used. The listing icon must be at least 128×128 pixels.

128 × 128Required

Listing Icon

Main icon on the addons.mozilla.org listing page. Required for submission.

48 × 48Recommended

Add-on Manager Icon

Shown in about:addons. If not provided, Firefox scales the 128px icon down.

32 × 32Recommended

Toolbar / Context Menu

Used in various browser UI contexts. Recommended for sharp rendering.

16 × 16Recommended

Small UI Icon

Used in tabs, address bar, and other compact UI locations.

Formats accepted: PNG or SVG

SVG advantage: A single SVG file scales to all sizes automatically

Screenshots

DimensionsAny size — no fixed dimensions required
Max file size3 MB per screenshot
Max count5 screenshots
FormatPNG or JPEG
RequiredNo, but strongly recommended for discoverability

Unlike Chrome, Firefox does not enforce specific screenshot dimensions. However, using consistent sizes (e.g., 1280×800) across all screenshots gives your listing a polished, professional look.

Promotional Images

Firefox Add-ons (addons.mozilla.org) does not use promotional images like Chrome's small tile, large tile, or marquee banners. The listing page relies on the icon and screenshots only. There is no equivalent to Chrome's promotional image system.

Text Limits

Name50 characters max
Summary250 characters max
DescriptionUnlimited — supports HTML formatting

Key Differences from Chrome Web Store

  • Firefox accepts SVG icons — Chrome requires PNG only.
  • Firefox screenshots have no fixed dimensions — Chrome requires exactly 1280×800 or 640×400.
  • Firefox has no promotional image system — Chrome has three promo tile sizes.
  • Firefox allows up to 5 screenshots — Chrome also allows up to 5 per language.
  • Firefox description supports HTML — Chrome description is plain text.

Publishing on both Chrome and Firefox? CWS Kit helps you create assets for Chrome, and the same screenshots work great on Firefox too.

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