The Chrome Web Store promo tile size
The Chrome Web Store uses a small promo tile of 440 x 280 pixels and an optional marquee promo tile of 1400 x 560, both JPEG or 24-bit PNG without transparency. The tiles are used when the store features or lists your extension.
How to make a good Chrome Web Store promo tile
Avoid small text and screenshots in the small tile: it is shown small. Use your logo and a few words on a solid background, and keep the marquee tile in the same style.
Questions
What size is a Chrome Web Store promo tile?
The Chrome Web Store uses a small promo tile of 440 x 280 pixels and an optional marquee promo tile of 1400 x 560, both JPEG or 24-bit PNG without transparency.
What size is the Chrome Web Store small promo tile?
440 x 280 pixels. The optional marquee tile is 1400 x 560.
Is my image uploaded anywhere?
No. The image is read and resized in your browser; nothing is sent to a server.
How does the resize work?
It scales the image to cover the target size and crops the overflow evenly from the edges, so nothing is stretched.