Allegro image tool

Test an Allegro thumbnail against the pure white rule before your listing goes live.

Marketplace

Drop a product photo here, or click to choose JPG, PNG or WebP. The photo is checked in your browser and never uploaded.

Report

Your pass or fail report appears here.

Quick answer

The Allegro image tool tests whether a photo meets Allegro's thumbnail rules: a pure white RGB 255, 255, 255 background, at least 500 px on the longer side, and an accepted file type. It also flags anything over 2560 px. It runs in your browser, so the photo is never uploaded, and it can export a fixed copy.

What this tool does

Pure white edge test
Reads the outer ring of pixels and passes only when almost all of them measure as true white.
Longer side size check
Fails photos under Allegro's 500 px minimum on the longer side and warns under our own 1000 px target.
Oversize flag
Flags any photo over 2560 px on its largest side, the size above which Allegro scales images down.
File type and weight
Tests for JPEG, PNG or WebP and compares the file with 20 MB, a ceiling that is our own figure.
Transparent edge check
Fails a cutout with see-through edges, because a transparent border does not measure as the white Allegro asks for.
Fix All export
Exports a JPEG at 1000 px on the longer side, flattens transparency onto white, then rechecks the new copy.

How to use it

1Add the photo you plan to use as your first image.
2Check the background, size and file type results.
3Export the fixed copy, or reshoot if only the background fails.

Allegro: The rules at a glance

Shape	Any
Minimum size	500 px
Recommended size	1000 px (our suggestion)
File size limit	20 MB (our suggestion)
Formats	JPEG, PNG, WEBP
Main image background	Pure white

Rules last checked: 2026-10. Official source

Allegro runs two sets of photo rules, and that catches sellers out. Its gallery rules allow any background colour, while its thumbnail rules ask for white measured as RGB 255, 255, 255. A photo can be fine in the third gallery slot and still be wrong as the first image.

This page tests the thumbnail case, because that is the one with a measurable colour. It reads the edge pixels of your photo in your own browser, so the file stays on your device.

When a non-white thumbnail is allowed

Allegro's thumbnail page lists real exceptions, so a failed background test here is not always a problem for you. Fashion, jewellery, bags and travel clothing may use a plain light grey with an HSV value of at least 0.8. Used, refurbished or damaged items on a regular account may use another background, and so may listed categories such as sofas, furniture sets, plants, wallpaper, cars and digital goods.

White and transparent products get no exception. A clear glass on white still has to be on white, so light it from behind to keep the edges visible instead of switching to a grey backdrop.

What counts as forbidden text

Allegro bans added text such as your store name or order information, and text describing product features. Text printed on the product or its original packaging is fine. In the gallery you may show numbers with units for dimensions, zoom circles and arrows, but the thumbnail takes no extra graphics at all, and that includes watermarks. Infographics are limited to invited sellers with BrandHub access.

Questions sellers ask

Why does my white Allegro background fail?

Allegro specifies standard white, RGB 255, 255, 255, and measured white is stricter than it looks. Phone photos usually record a white wall as light grey or cream. Brighten the backdrop in your editor or remove the background, then test the photo again here.

Is 500 pixels enough for Allegro?

It meets the stated minimum, which Allegro measures on the longer side. It is thin for a large screen, though, so this tool suggests 1000 px as our own target. Files above 2560 px are scaled down by Allegro, up to a 26 megapixel upload limit.

Can I show several angles in one Allegro thumbnail?

Yes, if each frame shows a different side or function, such as front, back and interior. Allegro warns against repeating the same view, because two copies of a garden set can suggest the listing includes twice as many pieces as it really does.

Do I need to label AI edited photos on Allegro?

Allegro says deepfake photos, meaning generated or heavily altered with AI, must be disclosed under the EU AI Act. A marking option appears in the listing form, the product catalogue, file listing and the API. Check whether your edit qualifies before you publish it.

What size should an Allegro product image be?

At least 500 px on the longer side, which is Allegro's stated minimum, in any shape. Allegro scales anything over 2560 px down and takes uploads up to 26 megapixels. This tool suggests 1000 px as our own target, because 500 px looks thin on a large screen.

Why would Allegro reject my thumbnail?

Start with its thumbnail rules: the background must be white, RGB 255, 255, 255, and added text, a seller logo, a watermark, a frame or icons are not allowed. This tool tests background, size and file type. Check text and logos by eye, because pixels cannot show them.

Is there a free tool to check Allegro thumbnails?

Yes, this page is free. Add a photo and it reports on the background, size and file type, then offers a fixed copy. The photo is read in your browser and is not sent to a server, so unpublished product shots stay on your device.

Can I upload WebP photos to Allegro?

Only through the API or file listing. JPG, JPEG and PNG work everywhere, so choose one of those if you use the normal listing form. This tool passes WebP because Allegro accepts it on those routes, so a pass does not mean every route takes it.

Can this tool turn my Allegro background white?

No. Fix All resizes, re-saves and flattens transparent areas onto white, but it cannot repaint a backdrop in a photo. If only the background fails, shoot again on white or use a background remover, then test the new file on this page.

How do I check an Allegro photo on my phone?

Open this page in your phone browser, tap the upload area and choose the photo from your gallery. The test runs on the phone itself. Phone shots of a white wall often read as light grey or cream, so expect the background result to need attention.