UploadSizer

How to make a photo under 100 KB

For forms that want a photo, signature or document image under a set size.

What decides the size

A phone photo is usually several megabytes, which is thousands of kilobytes. Two things decide how big a photo file is:

  • Pixel dimensions, such as 4000 × 3000. Fewer pixels means a smaller file.
  • JPEG quality. Lower quality throws away fine detail the eye barely notices, up to a point.

A good result uses the highest quality that fits and only reduces the pixels when it has to. That's what the compressor on this site does: it tries quality first, then steps the dimensions down until the file is under your limit.

Check the form's rules first

  • A maximum size, such as "under 100 KB". This is the number to enter.
  • A minimum size. Some forms reject files that are too small. For example, the US online passport renewal asks for a photo of at least 54 KB.
  • Pixel dimensions, such as "at least 600 × 600 pixels" or "no larger than 1200 pixels". Enter a maximum in the "Largest side" box.
  • File type. Most forms want JPG. iPhone photos are often HEIC; the compressor saves them as JPG unless you change the "Save as" setting.

Compress it

  1. Open Compress image to a size and choose your photos.
  2. Press 100 KB or 200 KB, or type the limit from the form.
  3. If the form gives a maximum width or height, enter it under "Largest side".
  4. Press Compress and download the result. Several images download together as a ZIP.

Compress an image

Keep it sharp

  • Crop first. Every pixel of background takes up space. Cropping to just the face, signature or document leaves more room for detail.
  • For ID photos, use the right tool. If the form wants a passport-style photo with set dimensions, use the passport and visa photo maker. It crops to the official size and checks the file limits.
  • Signatures: sign in dark ink on plain white paper and photograph it in good light. Plain backgrounds compress far better than shadows.
  • Start from the original. A photo that was already compressed or screenshotted loses more detail each time.

KB, kB and KiB

Forms rarely say whether 100 KB means 100,000 bytes or 102,400 bytes. This site uses the smaller number and aims about 2% under it, so the file fits under either.

Last updated 2026-10-23.