Listing sites reject oversized images, crop them unpredictably, or take an age to upload them. A few minutes of preparation avoids all three.
Check the destination's image rules before choosing dimensions or encoding. Show condition, labels and defects clearly; compression must not hide important product details. Inspect the saved photos at the size a buyer is likely to view.
The starting maximum width is 1920 pixels. Choose Keep original size when dimensions must remain unchanged.
JPG and WebP use the quality control. PNG ignores it; compare actual sizes because results can be larger.
Add all the photos for one listing at once and apply the same settings, a width of about 1600 pixels at the default quality. Every picture then comes out at a similar size and sharpness, and the listing looks consistent. The tool shows each file's size before and after, so you can see the total you are sending.
Crop each photo first if the product does not fill the frame, because a tighter picture is easier to see at thumbnail size. Put the best photo first, since that is the one buyers see in the search results.
Choose Keep original size instead of the default maximum width. JPG or WebP quality changes can reduce bytes but also affect visual detail.
JPG, PNG and WebP always open. Other types depend on your browser, so convert them first with Convert format. A very large photo can run out of memory on a phone, so try a computer.
There is no set limit. The practical limit is your device's memory, so a few dozen ordinary photos is no problem on a computer.