Most advice about exam photos is about making files smaller. Then you meet a form that says "minimum 20 KB" or, in MHT CET's case, "minimum 100 KB", and your carefully compressed photo is rejected for being too light. Here is which forms set a floor, why a small image physically cannot reach it, and what to do.
Forms with a minimum file size
From the official notices behind our exam pages:
| Exam or document | Minimum | Pixel size |
|---|---|---|
| MHT CET photo | 100 KB (max 5 MB) | 2 × 2 inch; no pixels given |
| UK passport digital photo | 50 KB | at least 600 × 750 px |
| Bank declaration (IBPS, SBI, RBI, LIC) | 50 KB | 800 × 400 px |
| NEET UG finger and thumb impressions | 50 KB | 800 × 600 px |
| India Post GDS photo / signature | 30 KB / 20 KB | 320 × 400 / 300 × 120 px |
| Bank photo and thumb (IBPS format) | 20 KB | 200 × 230 / 240 × 240 px |
| UPSC photo and signature | 20 KB | 550 × 550 / 350–500 px |
| NEET PG signature | 20 KB | 3.5 × 1.5 cm box at 200 DPI |
| HTET photo / signature / thumb | 20 / 10 / 10 KB | 3.5 × 4.5 cm photo |
| SSC, bank signatures, Sarathi photo and signature | 10 KB | varies |
Why a small image can't reach the minimum
A JPEG's size depends on how many pixels it has and how much detail is in them. When the form fixes a small pixel size, there is a ceiling on how heavy the file can get, even at the highest quality. We measured cleaned signatures at maximum JPEG quality:
| Signature size | At quality 90 | At maximum quality |
|---|---|---|
| 140 × 60 px (IBPS format) | 2.3 KB | 5.6 KB |
| 276 × 118 px (3.5 × 1.5 cm at 200 DPI) | 4.7 KB | 12.1 KB |
| 350 × 150 px | 6.3 KB | 16.3 KB |
| 472 × 157 px (SSC) | 7.5 KB | 19.3 KB |
So an IBPS-format signature cannot reach 10 KB by quality alone, and a NEET PG signature at 276 × 118 px cannot reach 20 KB. Photos are easier: a 200 × 230 px photo reached a median of about 48 KB at maximum quality in our test, comfortably above the 20 KB bank minimum.
Watch the definition of a kilobyte
If a form's minimum is 20 KB and it counts a kilobyte as 1,024 bytes, you need at least 20,480 bytes. A file of 20,100 bytes is "20.1 KB" on one system and "19.6 KB" on the other. Leave a margin above the minimum.
Three ways to make a file heavier
- Raise the quality. Always the first step, and it is all you need for most photos. The editor picks the highest quality under the maximum automatically.
- Use more pixels, if the form allows it. MHT CET gives no pixel size, so a larger image is fine: our 600 × 600 px photo (2 inches at 300 DPI) passes 100 KB. Don't do this when the form fixes the pixels.
- Pad the file. A JPEG can carry comment blocks that viewers ignore. Adding them raises the byte count without changing a single pixel of the image. This is what ExamFitr's editor does when the quality ceiling is below the minimum, and what the increase image size in KB tool does on its own. The portal sees a valid JPEG of the right size and dimensions.
Avoid the old trick of saving the image as a huge PNG and renaming it to JPG. The file header still says PNG and validators reject it.
Check before you upload
Right-click the file and open Properties (Windows) or Get Info (Mac) and look at the size in bytes, not the rounded KB. It should be above the minimum counted in 1,024s and below the maximum counted in 1,000s. The editor's green badge uses exactly that rule.