Pixel dimensions and file size get most of the attention when preparing exam documents, but format is just as strict a requirement — and just as easy to get wrong without realizing it, especially if your phone's default camera settings save photos in a format other than JPG. Checking across the exam specifications tracked on this site — SSC, RRB, IBPS, SBI, RBI, UPSC, NEET, JEE, GATE, and the state PSCs — one pattern is nearly universal: almost every document field specifies JPG or JPEG. GATE is the single exception, which additionally allows PNG for its photo and signature fields.
Why JPG Became the Standard for This Use Case
JPG uses lossy compression — meaning it can shrink a photo dramatically by discarding fine detail the eye barely notices, which is exactly what's needed to fit a passport photo into a 20-50KB budget or a signature into 10-20KB. PNG, by contrast, uses lossless compression: it preserves every pixel exactly, which is great for screenshots or graphics with sharp edges and flat colors, but produces much larger files for photographs — often several times the size of an equivalent JPG at similar visual quality. For a format built around hitting a tight KB target, JPG's compression behavior is simply the better fit, which is likely why exam portals standardized on it well before most of today's applicants started using them.
JPG is also universally supported — every browser, every government portal's upload validator, and every image viewer handles it without exception. PNG and WEBP support, while common today, wasn't always as consistent, and government IT systems tend to be built once and left largely unchanged for years, which favors the format that was already the safe default.
What Goes Wrong With PNG
Beyond the file-size problem, PNG has a specific technical issue for exam photos: transparency. If a PNG has any transparent areas (common in screenshots or edited images), and a tool converts it to JPG without properly filling that transparency, the result can render as solid black or an unexpected color instead of white — since JPG doesn't support transparency at all. A PNG source photo needs to be flattened onto a solid white background during conversion, not just have its extension changed.
Uploading a PNG where a portal expects JPG doesn't always fail loudly — some portals accept the file but the resulting document may still be rejected later during verification, or the file may simply exceed the KB limit because PNG compresses less efficiently for photographic content. If your portal's photo or signature field is behaving unexpectedly, checking the actual format of your file (not just its extension) is worth doing before troubleshooting anything else.
What Goes Wrong With WEBP
WEBP is a newer format that generally compresses better than both JPG and PNG, but it's far less consistently supported by government upload systems — many were built before WEBP existed and simply don't recognize it, rejecting the upload outright or throwing a generic error. Even though your phone or a modern browser might display a WEBP file just fine, that doesn't mean the exam portal's server-side validation will accept it. Converting to JPG before uploading avoids this entirely.
The HEIC Problem (iPhone Users, Read This)
Many iPhones save photos in HEIC format by default rather than JPG — a format that offers better compression but that almost no government exam portal recognizes. If you've taken your exam photo or signature scan on an iPhone and the portal's upload keeps failing with no clear reason, checking whether the file is actually HEIC (rather than JPG, despite what the Photos app shows you) is one of the first things to rule out. Converting the HEIC file to JPG before resizing solves this — see our HEIC to JPG converter for that step specifically.
Converting Before You Resize
If your source photo or signature is already in PNG or another non-JPG format, convert it before running it through an exam-specific resize tool, rather than assuming the resize tool will handle the conversion invisibly for you — checking the actual output format after processing is worth the extra ten seconds. The PNG to JPG converter handles the common conversion case directly, and general-purpose image compression tools can help further if the converted file still needs to shrink to hit a specific KB target.
The One Documented Exception: GATE
Based on the specification data tracked on this site, GATE is the one exam that explicitly allows PNG in addition to JPG/JPEG for its photo and signature fields — worth double-checking against the live GATE application portal for your specific year, since GATE's organizing institute can change portal rules each recruitment cycle. For every other exam covered here, treat JPG as the safe default unless the notification explicitly says otherwise.