"Maximum file size: 100 KB" is one of the tightest limits you'll see on an online form, and a modern phone photo can be forty or fifty times that size. Getting under it reliably takes two steps done in the right order: shrink the dimensions, then compress.
Why 100 KB Is So Small
A phone camera often shoots 12+ megapixel photos, producing files of 3–8 MB. That is roughly 30 to 80 times the 100 KB target. Compression alone, without resizing, usually can't close a gap that large without visibly damaging the image — which is why resizing first matters so much.
Step-by-Step
- Resize first. Open the Image Editor and reduce the photo to around 800–1000 pixels on the longer side. For a passport-style photo, follow the exact dimensions your form specifies instead.
- Compress. Upload the resized photo to Image Compress and download the result.
- Check the size. On a computer, right-click the file and check Properties; on a phone, check the file details in your gallery or file manager.
- Adjust if needed. Still over 100 KB? Reduce the dimensions a little further and compress again.
What to Expect at 100 KB
| Photo type | Typical result |
|---|---|
| Simple portrait, plain background | Usually easy to reach, looks clean |
| Busy background, lots of detail | May need extra resizing to stay sharp |
| Document scan/photo | Text can get soft — consider a PDF tool instead for documents |
| Screenshot with text | Better as PNG at a larger size limit if possible |
A Quick Reference Table
| Longer side (pixels) | Approx. size at moderate JPG quality |
|---|---|
| 1500 px | 300–600 KB |
| 1000 px | 100–250 KB |
| 700 px | 50–120 KB |
| 500 px | 25–70 KB |
These are rough guides — actual size depends on the photo's content, since a plain background compresses much better than a detailed one.
Common Reasons It Doesn't Work the First Time
- Skipping the resize step and only compressing — the file stays too large or quality drops badly trying to force it.
- Uploading a screenshot of the photo instead of the photo itself, which adds extra pixels and often a border.
- Starting from a HEIC file — convert with HEIC to JPG first, since HEIC files can behave unpredictably in some tools.
- Forgetting the format — PNG rarely gets small enough for a photo; use JPG.
After You're Under the Limit
Open the compressed photo at full size on your screen and check that:
- Your face (or the document, if it's a scan) is still clearly recognisable.
- There's no visible blockiness in flat areas like sky or walls.
- Colours look close to the original.
If quality has dropped too much, go back and use a slightly larger size — most forms set 100 KB as a maximum, and a photo at 90 KB that looks great beats one squeezed to 60 KB that looks rough.
For photos going onto forms with pixel-dimension requirements as well as a size limit, see how to reduce photo size for online forms. For the underlying idea of pixels and DPI, read what is image resolution and DPI.
