Where 20 KB limits are used
Very small limits such as 20 KB are common for photographs, signatures and thumb impressions in government recruitment, exam and admission forms. Systems that handle millions of applications keep each file tiny, so a normal phone photo of 2–4 MB is about a hundred times too large.
What happens when you resize
The picture is saved as a JPG, and the tool lowers the JPG quality step by step and, only if needed, the pixel size, until the file is under 20 KB. If the form also asks for exact pixel dimensions, such as 200 × 230 pixels, type them in the width and height boxes. The final KB size and pixel size are shown before you download.
What quality to expect
A face photo or signature can look perfectly fine at 20 KB when it has the right pixel size. Problems come from large camera photos that must be squeezed hard — cropping to the face first leaves more of the 20 KB for the important part.
Common problems and how to fix them
The face is too small in the result: crop the photo first with Crop Image or Passport Size Photo Maker. The form needs a minimum size too, such as 10–20 KB: use Signature Resize, which supports a KB range. The picture looks blocky: the pixel size you entered is large for 20 KB; check if the form allows smaller dimensions.
Good habits
Read the form's photo rules carefully, keep your original photo, and check both the KB size and the pixel size shown before uploading.