Firefox Add-on Icon and Screenshot Sizes (2026)

I read Mozilla's Extension Workshop guides and the Firefox Add-ons developer docs on 9 November 2026. I also checked the images on the 100 most used Firefox extensions.

This post covers the icon, screenshots, the summary and what popular add-ons actually upload.

Firefox add-ons are listed on addons.mozilla.org, which Mozilla calls AMO. Its image rules are spread across three official sources.

1. 1Mozilla's guide to an appealing listing on Extension Workshop, which covers screenshots, icons and the summary.
2. 2The Firefox Add-ons API docs, which state the rules for uploaded icons.
3. 3MDN's manifest icons page, which covers the icon Firefox shows after someone installs your add-on.

Each source covers a different job. So you'll need images for the listing page and a separate set inside your add-on package.

Here's the full set in one table.

Firefox doesn't ask for a banner or a promo tile. That makes its listing simpler than most stores.

The listing icon is the image people see on your AMO page and in search results. You upload it in the Developer Hub, not inside your add-on.

The API docs set the rules. The image must be square, in JPEG or PNG format, and Mozilla recommends 128 x 128 pixels. AMO then resizes it to icons 32, 64 and 128 pixels wide.

Extension Workshop's listing guide mentions two resolutions, 32 x 32 and 64 x 64. Since AMO also serves a 128 pixel version, a 128 x 128 upload covers every size.

The same guide suggests keeping your source file in SVG or a similar vector format. That way, you can export a sharp PNG at any size later.

Mozilla's listing guide says your icon could matter as much as your add-on's name. An eye-catching icon draws people in from a category list or a search.

It gives two tips. First, make the icon match what your add-on does, like a notepad for a notes add-on.

Second, skip words and letters unless they're part of a known brand. You use one icon in every language, so text may not make sense to everyone.

Test it at 32 x 32 before you upload. That's the smallest size AMO makes, and fine lines tend to vanish there. One strong shape on a plain background survives best.

Your add-on package needs its own icons too. These go in the icons key of your manifest.json file, and Firefox shows them after someone installs your add-on.

MDN's guidance says to supply an icon of ideally 32 x 32 pixels. That's the default icon in the add-ons manager.

For high resolution screens, add a version at double the size, such as 64 x 64. Firefox looks at the screen and picks the icon that fits best.

You can also use one SVG file for every size. But you still list each size in the manifest, with the same SVG file for each one.

Mozilla's listing guide recommends screenshots of 1280 x 800 pixels. It calls that the maximum image display size, so larger files won't look any bigger on your page.

For other sizes, it recommends a 1.6 to 1 shape. That means the width is 1.6 times the height.

Laptop screens with a 16 by 10 display use this shape. A full screen capture from one of them fits without any cropping.

There's no practical limit to the number of screenshots, Mozilla says. But it warns against adding them just because you can.

Each screenshot should show one key feature. If two screenshots show the same thing, cut one.

You can also reorder them. Mozilla suggests putting them in an order that tells a story about your add-on's features.

A simple order works for most add-ons. Show the main feature first, then the settings that make it useful, then anything extra. The top extensions, as you'll see below, mostly upload between two and six.

Mozilla says you shouldn't be afraid to annotate your screenshots. Arrows, boxes and short labels help people see what matters.

There's a catch, though. You can only upload one set of screenshots, and every language uses it. But you can translate the caption for each screenshot.

So the guide suggests a balance. Annotate to point at features, and explain the annotations in the caption, where you can translate them.

In practice, keep any words inside the image short. Let the caption carry the full sentence. Our guide to screenshot caption copy covers how to write captions that people actually read.

I pulled the 100 most used Firefox extensions from the AMO API on 9 November 2026. AMO listed 116,785 extensions that day. The top one, uBlock Origin, had about 11.5 million average daily users.

The API listed icons at 32, 64 and 128 pixels for every one of the 100. That's expected, since AMO makes those sizes from your upload.

Screenshots varied more. The middle extension had 4 screenshots, and the most was 13. Only 4 of the 100 had none.

So nearly every popular extension shows at least one picture of itself working. Most stop well short of ten.

Those 100 extensions had 396 screenshots between them. I counted the size of each one.

Almost half were exactly 1280 x 800. In all, 261 of the 396 used the 1.6 to 1 shape.

AMO also stores a small thumbnail of each screenshot. Most thumbnails in my sample were 533 pixels wide.

Your summary is the short text under your add-on's name. Mozilla limits it to 250 characters, but it says not to treat that as a target.

Keep it as short as you can while naming your main features and why they help. Be direct.

Among the top 100 extensions, the middle summary ran to 104 characters. Only 18 went past 200.

The full description has no practical limit. Even so, Mozilla's advice is not to write a novel. Explain why the add-on matters to the user, not just what it does. Think about the words people search for, and add them as tags in the Basic Information section.

Firefox themes are a separate kind of add-on, and there are far more of them. AMO listed 515,628 themes on 9 November 2026.

A theme's images don't follow the screenshot rules above. Its colors and images are set in its own manifest.json file. The simplest theme changes only colors and needs no image at all.

Image themes use keys like theme_frame and additional_backgrounds. Mozilla's theme guide says that from Firefox 156, a backgrounds_area setting decides where they're drawn. They can cover the whole window or only the toolbars at the top.

If you make a theme, check how it looks in Firefox itself before you submit.

If your extension also runs in Chrome, you can reuse much of the artwork. The Chrome Web Store asks for 1280 x 800 screenshots too.

So a single set of 1280 x 800 screenshots works for both stores. That saves you a full round of design work.

The icons are close as well. Chrome uses a 128 x 128 store icon, and Firefox recommends the same size for its listing icon.

What doesn't carry over is Chrome's promo tiles. The Firefox listing has no upload for them. Our guide to Chrome Web Store image sizes lists every image Chrome needs.

Run through this list before you send your add-on for review.

1. 1A square PNG or JPEG listing icon, ideally 128 x 128.
2. 2Icons in your manifest at 32 x 32 and 64 x 64, or one SVG listed for both.
3. 3Screenshots at 1280 x 800, or another 1.6 to 1 size.
4. 4One screenshot for each key feature, in a sensible order.
5. 5Captions that explain any arrows or labels in your images.
6. 6A summary well under 250 characters, with your main benefit first.

If every item checks out, your listing is ready.

We make PlayMockUp, so weigh this part with that in mind. Our tool frames screenshots in phones and tablets for app stores. It doesn't make 1280 x 800 desktop screenshots.

That limits what it can do for most Firefox add-ons. They run on desktop, so plain browser screenshots show them best.

There's one exception. Firefox for Android supports add-ons too. If yours works there, a phone frame shows that clearly in a single image.

You can frame a phone screenshot in our free mockup generator. Then check that your final image still matches the 1.6 to 1 shape before you upload it.