Photo and signature rules: pixels, KB and DPI

The short answer

• Pixels are how wide and tall the image is on screen (for example 200 × 230).
• KB is how heavy the file is (for example 20–50 KB).
• DPI is how pixels map to centimetres when printing. Online forms that only list pixels usually ignore DPI.

You often need both the right pixels and the right KB band. Start with the Exam photo resizer.

Pixels vs file size vs print size

Meeting only pixels, or only KB, is a common reason for rejection. See Why your upload was rejected.

Aspect ratio

Aspect ratio is width divided by height. A 200 × 230 photo is not the same shape as a square selfie.

1. Crop to the face framing and ratio the bulletin implies.
2. Resize to the exact pixel box.
3. Compress into the KB band.

Stretching to force the box warps faces. Prefer Crop image, then resize.

How DPI converts centimetres to pixels

When a notice or a print shop gives a size in centimetres and a DPI:

pixels ≈ centimetres ÷ 2.54 × DPI

Arithmetic only: at 300 DPI, 3.5 cm is about 3.5 ÷ 2.54 × 300 ≈ 413 px. At 300 DPI, 4.5 cm is about 531 px.

If the form lists only pixels, use those pixels. Do not invent a DPI. If it lists only centimetres for an online upload, look for a pixel table in the same PDF. Many bulletins include both.

Why stay a little under the maximum KB

Portals enforce a ceiling. A file that one device calls “50.2 KB” may fail a “maximum 50 KB” rule. Aim inside the band and slightly under the maximum. If a minimum KB exists, which is common for signatures, do not crush the image into a near-empty white field. Some portals also strip extra data from a JPEG, or they measure the picture again after upload. Raising the file with blank comment data is not a substitute for a sharper save. Move the quality control up first. The exam pages explain the size each notice actually states: exam photo and signature size.

Photo rules vs signature rules

Photo (a typical pattern — verify every time): front face, plain background if required, face occupying a stated share of the frame, ears visible, no mask when the bulletin says so, colour JPG in a stated pixel box and KB band.

Signature (a typical pattern — verify every time): dark pen on white paper, a wide short pixel box, often a smaller KB band than the photo. Too thin a stroke and the file can fall under the minimum.

Size each file with the Exam photo resizer. If the portal wants one combined image, use Join photo and signature after both meet their own rules.

Worked example (made-up bulletin numbers)

Example from the IBPS CRP PO/MT-XVI annex, which is not the rule for every form: photo 200 × 230 px, 20–50 KB, JPG; signature 140 × 60 px, 10–20 KB, JPG. The same annex also describes the photograph as 4.5 cm × 3.5 cm. That centimetre line is not 200 × 230 px. See IBPS photo and signature size.

1. Photo: preset or custom 200 × 230 and 20–50 KB, then download.
2. Signature: custom 140 × 60 and 10–20 KB, then download.
3. Upload into the correct fields. Do not swap the files.
4. If one stacked image is required, join them after both are sized.

Reading a bulletin

1. Search the PDF for photograph, signature, KB, pixel and dimension.
2. Note format, width × height, minimum KB, maximum KB, and any face or background rules.
3. Note live-photo or webcam steps separately. Size tools do not replace them.
4. Prepare the files, then upload on a stable connection.

More on one exam: UGC NET December 2026 photo and signature checklist, CSIR-UGC NET December 2026, and JEE Main 2027 Session 1. The combined workflow is in Exam photo and signature size.