Compress Thumb Impression to 20KB
SSC exams (CGL, CHSL, MTS) require thumb impression files under 20KB. This tool compresses your scanned fingerprint while preserving ridge detail - so the print stays readable after upload.
checklistSSC Thumb Impression Requirements
Why thumb impressions get rejected
Smudged ridges
Too much ink applied. Ridge lines merge into a blob and the portal flags it as unreadable.
File too large
Raw phone photos are often 2-5 MB. SSC requires under 20KB - a 100x reduction.
Wrong format
Uploaded as PNG, HEIC, or PDF instead of the required JPG/JPEG format.
Too light
Not enough ink on the thumb. Fingerprint ridges are barely visible after compression.
How to get a clean thumb impression under 20KB
- Wash and dry your hands to prevent smudging and excess moisture.
- Press your left thumb firmly (but not too hard) onto a blue or black ink pad. Too much pressure blurs the ridges.
- Press once onto clean white paper. Do not roll your thumb - a single, steady press gives the sharpest ridge pattern.
- Scan at 200 DPI using a scanner app (like Adobe Scan or Microsoft Lens) or a flatbed scanner.
- Crop closely around the thumb print to remove unnecessary white borders.
- Use the compressor above to bring the file under 20KB while keeping ridge lines clear.
Frequently Asked Questions
What is the thumb impression size limit for SSC exams?
SSC CGL, CHSL, and MTS exams require the left thumb impression to be between 10KB and 20KB in JPEG format. Files exceeding 20KB are rejected during upload.
Left thumb or right thumb?
Most Indian government exams require the left thumb impression. However, always check the specific exam notification. If your left thumb is injured or amputated, the right thumb is accepted with a declaration.
What if my thumb impression is already under 20KB but still rejected?
The rejection may be due to format (PNG instead of JPG), wrong aspect ratio, or the ridges being too faint to read. Try scanning with more ink and better lighting, then compress again.
Can I use a phone camera instead of a scanner?
Yes, but ensure even lighting and no shadows. Scanner apps like Adobe Scan or Microsoft Lens straighten the image automatically. Natural daylight near a window works best for phone photos.