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Increase an image's file size in KB

For forms that reject files below a minimum, such as 20 KB. Quality is raised first; if the picture is simply that small, the file is topped up with an invisible comment.

Private by design

Every transformation runs in your browser. We could not see your images if we wanted to.

Why a form would reject a small file

Most people meet a maximum file size. Some portals also set a minimum, such as 20 KB, and reject anything under it. The reason is practical: a very small file is often a blank page, a badly scanned document or a corrupted upload, so a minimum is a cheap way to catch obvious mistakes. The side effect is that a perfectly good picture that happens to be small, such as a signature on a plain background, can be turned away for being too light.

How the size is increased

There are two steps, in this order:

  1. Save at a higher quality. If the picture was compressed hard, saving it again at a higher setting writes a larger file. Nothing about the visible picture gets worse.
  2. Top up with a comment. If the image is simply that small, for example a plain signature, a higher quality cannot reach the minimum. The tool then adds an invisible comment of spaces to the file until it reaches the size you need. Image viewers ignore it, so the picture looks identical.

The tool is for meeting a technical minimum on a picture that is already genuine. It does not make a bad scan better and it should not be used to disguise a file the portal is right to reject.

Setting a range

Many portals specify both limits, for instance 20–50 KB. This page starts with 20–50 KB; change either value in the file size card and the result lands between the two. Set the format and the dimensions at the same time if the form requires them, so you produce one file that satisfies everything.

Check these before you upload

  • Format. JPG is accepted nearly everywhere; some forms refuse PNG or HEIC.
  • Dimensions. Some portals ask for exact pixel sizes as well.
  • The image itself. Make sure it is the right file and is clear and readable.
  • The official rules. Limits change between years and exams. Use the portal’s current notice as the source of truth.

If you need the opposite, to make a file smaller, see compress to 50 KB or 100 KB. For exam portals with their own preset sizes, the exam photo and signature size chart lists them. The file is processed in your browser and is never uploaded.