Short answer: most forms check the file size in KB strictly, and many also check the pixel size (width × height). If the notice gives both, your photo must match both. If it gives only KB, keep the photo close to the shape asked for (usually a passport-style portrait), and the pixels matter less.
KB and pixels are not the same thing
| Pixels (dimensions) | KB (file size) | |
|---|---|---|
| What it means | How many dots wide and tall the image is | How much storage the file takes |
| Example | 200 × 230 px | 20 KB to 50 KB |
| How to see it | Photo details / properties: "Dimensions" | Photo details / properties: "Size" |
| How to change it | Resize or crop | Compress (lower quality) or resize |
The two are linked: fewer pixels usually means fewer KB. A phone photo is often 3000 × 4000 px and 2–4 MB. Shrinking it to 200 × 230 px brings it down to a few dozen KB, often without visible quality loss on screen.
A real example
A student asked: "My photo is 413 × 513 pixels and 284 KB. The form says 20 KB to 50 KB. Will it be rejected?"
- 284 KB is far above 50 KB, so the form will refuse the upload, whatever the pixels are.
- 413 × 513 px is a normal 3.5 × 4.5 cm passport shape. If the notice doesn't ask for an exact pixel size, it's fine.
- Fix: compress the same photo to about 40 KB. At 413 × 513 px that's easy, and the face stays sharp.
How to tell what your form checks
- Read the photo section of the official notification. Look for words like "pixels", "px", "dimensions" or "width × height".
- If you see pixels: make the photo exactly that size (or inside the range given), then check the KB.
- If you see only KB: keep the normal portrait shape and just bring the file inside the KB range.
- If you see cm or mm (like 3.5 × 4.5 cm): the form wants that shape. Any pixel size with the same proportion usually works, such as 350 × 450 px.
What about DPI?
DPI only matters when a photo is printed. For an online upload, almost no form checks DPI, so you can ignore it unless the notice specifically mentions it.
Common mistakes
- Only compressing, not resizing: a 4000-pixel photo squeezed to 20 KB looks blurry. Resize first, then compress.
- Stretching the photo to hit exact pixels: the face looks wide or thin. Crop instead of stretching.
- Going below the minimum KB: many forms also have a minimum, like 10 KB or 20 KB. Too small is rejected too.
The exam photo and signature resizer does all of this in one step: it sets the exact pixels for common exams, crops instead of stretching, and keeps the file inside both the minimum and maximum KB.