The short answer
| Upload | Use | Why |
|---|---|---|
| Photo of a person | JPG | Far smaller for the same look; what forms ask for |
| Signature or document photo | JPG | Forms with KB limits almost always ask for JPG |
| Screenshot, logo or graphic | PNG, unless the form says JPG | Sharp edges and flat colour, sometimes transparency |
| Form says "JPG or PNG" | JPG for photos, PNG for graphics | Pick the one that fits the KB limit |
Why forms ask for JPG: measured
JPG is built for photos: it discards detail you can't see to make files small. PNG keeps every pixel exactly, which suits graphics but makes photos huge. We saved two camera photos both ways with our converter:
| Photo | As JPG (original) | As PNG |
|---|---|---|
| Portrait, 26 megapixels | 2.71 MB | 27.7 MB (10×) |
| Indoor selfie, 24 megapixels | 2.14 MB | 23.5 MB (11×) |
A form with a 50 KB limit can be met with a JPG of a face at about 610×910 to 680×1010 pixels in our tests (see compress to 50 KB). A PNG photo would have to be shrunk to a tiny size to fit, which is why "file too large" errors often come from PNGs.
Screenshots are different. Our 1280×800 screenshot of form text was 38 KB as PNG, 44 KB as JPG at High (92%) and 35 KB at Good (80%). For flat graphics JPG saves little and blurs the edges of text slightly, so PNG is the better choice when the form allows it.
What happens if you upload the wrong one
- Rejected as the wrong type: many portals check the format and refuse PNG outright.
- "File too large": a PNG photo is often ten times the size of the same photo as a JPG.
- A renamed file: changing ".png" to ".jpg" doesn't change the contents. Portals that check the file itself still see a PNG.
Converting properly
Choose your file in the tool on this page, open the Convert tab, set Convert to to JPG and tap Convert. The result is a real JPEG with the same pixel size. JPG has no transparency, so transparent areas become white, which is what form photos and signatures need. If the form also has a KB limit, tap Keep editing this result and use Exact KB. iPhone photos in HEIC format convert the same way (HEIC to JPG).
JPG and JPEG
They're the same format. ".jpg" and ".jpeg" are two spellings of the file extension; a form asking for JPEG accepts a .jpg file, and the other way round.
Frequently asked questions
Can I just rename a PNG to .jpg?
No. The contents stay PNG, and portals that check the file will reject it or fail to read it. Convert it instead.
Are JPG and JPEG different?
No. They're two spellings of the same format's file extension.
Why is my PNG photo so large?
PNG keeps every pixel exactly. In our test a 2.71 MB JPG photo became 27.7 MB as PNG.
Which is better for a signature?
JPG, if the form asks for it, which most do. Crop to the signature and use the form's preset or Exact KB.
Which is better for screenshots?
PNG keeps text sharp and is often no bigger: our screenshot was 38 KB as PNG and 44 KB as JPG at High quality. Use JPG only if the form demands it.
Does converting to JPG lower the quality?
Slightly, and not visibly at High (92%). For a photo, converting from PNG to JPG mostly removes data you couldn't see anyway.
What about WebP or HEIC?
Most forms reject both. Convert them to JPG with the same tool.