Free online image resizer

For an online form, start with the form's rules. Most give a size in cm or pixels and a file limit in KB. Pick the matching ready-made size above, such as Passport Photo, Signature Resize or Stamp Size Photo, and the page opens with the size, the crop shape and the KB limit already set.

For India, the Indian passport page follows the Passport Seva rules, square ID pictures have their own 1x1 and 2x2 pages, and a scan of a card prints at true size from the ID card or Aadhaar card page.

For printing, pick a paper or photo size, such as a US wallet size photo, or type your own in cm or in inches. The tool writes 300 DPI into the file, so a 3.5 x 4.5 cm photo prints at exactly 3.5 x 4.5 cm when you print at 100%. For screens and social media, pick the platform or type pixels.

Resizing changes the width and height. It also makes the file smaller, but when a form gives a limit in KB, like 20 KB or 50 KB, use the compressor as well: it reduces the file size without changing the pixel size.