Chrome Web Store image size checker
Select the images of your Chrome Web Store listing. The checker reads the width, the height and the file type from the bytes of each file. It then finds the store image with that size and shows Pass, Check or Fail. For a 128x128 PNG icon it also measures the box of visible pixels and the transparent padding around it.
The checker reads the files in your browser. It does not upload them. It does not say that the store will accept your listing. The rules come from four pages on developer.chrome.com. The table below gives the text of each rule and the "Last updated" date of its page. The sentence above the table gives the date we fetched the pages.
Check your images
Your store images are checked.
I make these free tools alongside 108 Chrome extensions that 150,000+ people use. If this one helped, buy me a coffee. It honestly makes my day.
You're officially a regular.
This is visit . Regulars are the reason I keep these tools running. If they're part of your routine now, a coffee says thanks better than anything.
How the checker decides
- Size and type. For a PNG file the checker reads the IHDR chunk. For a JPEG file it reads the frame header. It does not use the file name.
- End of file. The checker walks the chunks of a PNG file to its end chunk (IEND) and the segments of a JPEG file to its end marker (FFD9). A file without it gets Fail as incomplete.
- Store image. The size selects the store image:
128x128is the icon,1280x800or640x400is a screenshot,440x280is the small promo tile and1400x560is the marquee promo tile. Any other size is a Fail. - Format. The icon must be a PNG file. The dashboard page asks for a PNG or JPEG file for the two promo tiles. The fetched pages do not give a file format for screenshots.
- Transparency. A PNG has an alpha channel when its color type is 4 or 6. A tRNS chunk gives simple transparency to the other color types. The images page describes only an image "that has no alpha", so a PNG with only a tRNS chunk gets Check.
- Icon padding. The checker finds the box of pixels with an alpha value above 0. It compares the box with the rule for a square icon: 96x96 artwork and 16 pixels of transparent padding per side. These are design rules ("should"), so a difference gets Check, not Fail. An icon with no visible pixels gets Fail.
- Totals. After all files are read, the checker shows each store image as given, missing or optional. It also counts the screenshots against the maximum of 5.
The rules in the official pages
Each row quotes the fetched text. All four pages were fetched on 2026-10-15.
| Image | Text in the source | Source and its "Last updated" date |
|---|---|---|
| Required images | "Only the extension icon, a small promotional image, and a screenshot are mandatory." | Supplying Images, last updated 2018-06-11 |
| Required images | "you must provide the following promotional images and video, with the exception of the Marquee promo tile, which is optional". The list includes "A link to a YouTube video that showcases your extension features." | Complete your listing information, last updated 2020-12-07 |
| Icon size | "You must provide a 128x128-pixel extension icon image in the ZIP file of your extension." | Supplying Images, last updated 2018-06-11 |
| Icon size | "A 128x128 px to use as your store icon." | Complete your listing information, last updated 2020-12-07 |
| Icon format | "The image must be in PNG format." | Supplying Images, last updated 2018-06-11 |
| Icon artwork | "The actual icon size should be 96x96 (for square icons); an additional 16 pixels per side should be transparent padding, adding up to 128x128 total image size." | Supplying Images, last updated 2018-06-11 |
| Icon artwork | "For other icons that are squarish, make the artwork's width 75-80% of the total width of the image. A circular icon should have a diameter of approximately 112 pixels, or 85% to 90% of the image width." | Supplying Images, last updated 2018-06-11 |
| Icon without alpha | "If you upload an image that has no alpha, it will be placed in a frame with rounded corners (12-pixel corner radius)." | Supplying Images, last updated 2018-06-11 |
| Screenshot size | "Square corners, no padding (full bleed)" and "1280x800 or 640x400 pixels" | Supplying Images, last updated 2018-06-11 |
| Screenshot size | "1280x800 or 640x400 pixels." | Creating a great listing page, last updated 2024-08-02 |
| Screenshot size and count | "At least one 1280x800 px screenshot, up to 5 total." | Complete your listing information, last updated 2020-12-07 |
| Screenshot count | "You must provide at least 1" and "preferably the maximum allowed 5" | Supplying Images, last updated 2018-06-11 |
| Small promo tile | "Small: 440x280 pixels (required)" | Supplying Images, last updated 2018-06-11 |
| Small promo tile | "A PNG or JPEG file that is 440x280 px to use as the small promo tile." | Complete your listing information, last updated 2020-12-07 |
| Small promo tile | "Extensions that don't have a small promotional image will be shown after extensions that do have that image." | Supplying Images, last updated 2018-06-11 |
| Marquee promo tile | "Marquee: 1400x560 pixels" | Supplying Images, last updated 2018-06-11 |
| Marquee promo tile | "A PNG or JPEG file that is 1400x560 px to use as the marquee promo tile." | Complete your listing information, last updated 2020-12-07 |
| Missing images | "If your product has a blank description field or is missing an icon or screenshots, it will be rejected." | Listing Requirements, last updated 2024-07-10 |
Where the sources do not agree
- Screenshot size. The images page and the best-listing page give "1280x800 or 640x400 pixels". The dashboard page names only "1280x800 px". The checker shows Pass for 1280x800 and Check for 640x400.
- Required items. The images page names three mandatory images. The dashboard page also lists a YouTube video link among the items that "you must provide".
- Promo tile format. Only the dashboard page names a format for the promo tiles ("A PNG or JPEG file"). The images page gives the size only.
- Icon format. Only the images page names a format for the icon ("The image must be in PNG format"). The dashboard page gives the size only.
Limits of this checker
Does the checker upload my files?
No. The page reads each file with the File API and decodes it with the image decoder of your browser. It sends no image data over the network.
Why can the shown size differ from the size in the file?
A JPEG file can have an EXIF orientation tag that turns the image on the screen. The checker uses the size in the frame header of the file. When the browser shows the image turned, the checker shows Check and gives both sizes. The fetched pages do not say which size the store uses.
Does it check the quality of the artwork?
No. It checks the pixel size, the file type, the transparency of an icon and the box of visible pixels in an icon. It does not test every byte of the image data, so a damaged file can still get Pass. A JPEG file with stray bytes between its segments, or with more than 4 MB of data before its frame header, can get Fail even when the browser can show it. The design advice on the images page, for example about shadows and text, is not checked. To test the match patterns of an extension manifest, use the match pattern tester.