What size is a 3x5 flag in pixels?

A 3x5 ft flag is 36 by 60 inches, so the pixel size depends on resolution. At 100 pixels per inch it is 3600 x 6000 pixels. At 150 pixels per inch it is 5400 x 9000. Any image with a 3:5 ratio, such as 1200 x 2000, has the right shape.

The ratio matters more than the exact number. If your file is 3:5, a printer can scale it to 3x5 ft without stretching or cropping. Otherwise it gets cropped or stretched, so set the flag proportion to 3:5 in the flag maker before you start designing.

Ask your printer what resolution they want, since requirements vary. The easier route is to download an SVG. SVG is a vector format, so it stays sharp at any size. The custom flag printing guide covers this, and the flag ratios guide lists pixel sizes for 2:3, 3:5 and 1:2.