I run a small AI product-photo tool for e-commerce sellers, and the same three questions come up every week: how big does my Amazon main image need to be, what does Etsy crop my thumbnail to, and why does Shopify reject my upload? The answers are spread across Seller Central, the Etsy Seller Handbook and the Shopify Help Center, so here is the condensed version I keep coming back to, plus a small checker I built that runs entirely in the browser.
Everything below is summarised from the marketplaces’ published guidelines as of September 2026. Rules vary by category, so confirm in the official docs before you bet a listing on it.
Amazon
Rule Value Minimum size 1000 px on the longest side Recommended 1600 px or more on the longest side (enables zoom); max 10,000 px Background (main image) Pure white, RGB 255,255,255. Off-white and gradients fail the automated check Product in frame 85% or more of the image area, fully in frame, in focus Not allowed on the main image Text, logos, watermarks, borders, props, hands, multiple views File JPEG preferred; PNG, TIFF, non-animated GIF accepted; sRGB or CMYKOnly the main image has to be white. Images 2–7 can be lifestyle scenes, infographics, size charts.
Etsy
Rule Value Recommended size 2700 × 2025 px (4:3) Minimum for zoom Shortest side at least 2000 px Thumbnail crop 4:3 in search results, 1:1 in some placements. Keep the product centred with room on every side Photo count Up to 20 photos and 2 videos per listing File JPG, PNG or GIF; sRGBEtsy has no white-background rule. What bites people is the 4:3 crop: a tall, tightly framed photo loses its top and bottom in search.
Shopify
Rule Value Recommended size 2048 × 2048 px, square Zoom threshold Larger than 800 × 800 px Upload limit 4472 × 4472 px (20 megapixels) or 20 MB File JPEG, PNG or WebPThe rule that actually affects conversion on Shopify is consistency: pick one aspect ratio for the whole catalog so collection grids line up.
The three mistakes I see most
- “White” that isn’t 255. A studio backdrop photographed under warm light comes out at 250/248/245. Looks white to you, fails Amazon’s check.
- Product too small in frame. Phone shots with lots of table around the product land at 50–60% fill. Amazon wants 85%.
- Mixed ratios on Shopify. One square, one portrait, one 4:3, and the collection page looks broken.
The checker
I got tired of eyeballing this, so I wrote a page that does the checks client-side:
- decodes the image on a Canvas, so nothing is uploaded anywhere and the file is gone when you close the tab
- samples the outer 2% ring of pixels and counts how many have every channel at 250 or above; under ~98% white usually means an off-white or gradient backdrop
- estimates product fill from the bounding box of pixels that differ from the backdrop colour, compared to the longest frame dimension (on a busy background it says “can’t measure” instead of guessing)
- checks dimensions and file size against all three platforms at once and prints pass / warn / fail per rule
It’s free and needs no account: https://bestpng.com/tools/marketplace-image-checker
If you spot a rule that has changed or a category exception I missed, tell me in the comments and I’ll update both this post and the tool.