Compress an image for an SSC signature
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Process 1–10 images, one at a time. Up to 20 MB per image and 100 MB total. Files stay on this device.
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Choose a photo or scan, set the file-size limit of your form, then download the result. The original is never changed.
Does my image get uploaded?
Images are processed in this browser, without image uploads, ads or analytics. Your language choice is stored locally. Public site files are saved only if you enable offline use; selected images and results are not saved.
What should I know?
One JPG, PNG or WebP. Choose JPG or supported WebP for a KB target; PNG optimization accepts PNG only, preserves pixels and has no KB target. PNG: up to 8 MP, 16,384 pixels per side and 64 MB decoded scanlines. Batch: 1–10 files, 20 MB each, 100 MB total. A verified basic HEIC opens in Safari, which decodes it natively; Chrome and Firefox cannot open HEIC. HDR, animation, unusual orientation and unsupported colour profiles are refused. Optional batch does not accept HEIC. GIF and SVG are unsupported.
The SSC signature at both sizes the notices give
SSC asks for the signature as a JPG of 10 to 20 KB. The main text of the CGL and CHSL notices gives about 6.0 × 2.0 cm; their annexures give about 4.0 × 2.0 cm. The notices we read give no pixel size, so we turned both into pixels at the 300 DPI the GD notice uses, and ran 4 signature styles through this page's 20 KB preset.
About 6.0 × 2.0 cm, as 709 × 236 px
| Signature | Bytes | KB of 1,000 bytes | KB of 1,024 bytes | In range | Room under the cap | Quality | Similarity |
|---|---|---|---|---|---|---|---|
| Thin pen on white | 13,501 | 13.50 | 13.18 | yes | 6,499 | 0.92 | 1.000 |
| Thick marker | 15,348 | 15.35 | 14.99 | yes | 4,652 | 0.92 | 1.000 |
| Grey scan with noise | 19,920 | 19.92 | 19.45 | yes | 80 | 0.78 | 0.857 |
| Phone photo with a shadow | 18,257 | 18.26 | 17.83 | yes | 1,743 | 0.82 | 0.961 |
Source: our test on 2026-11-10 (harness eacd79c, site code eacd79c), headless Chromium 145 on a desktop Mac, 4 images we made. Similarity is our own 8×8-block luma score (SSIM): 1.000 means no visible change. How we test
About 4.0 × 2.0 cm, as 472 × 236 px
| Signature | Bytes | KB of 1,000 bytes | KB of 1,024 bytes | In range | Room under the cap | Quality | Similarity |
|---|---|---|---|---|---|---|---|
| Thin pen on white | 10,200 | 10.20 | 9.96 | no, under it if a KB is 1,024 bytes | 9,800 | 0.92 | 1.000 |
| Thick marker | 12,351 | 12.35 | 12.06 | yes | 7,649 | 0.92 | 1.000 |
| Grey scan with noise | 18,930 | 18.93 | 18.49 | yes | 1,070 | 0.83 | 0.865 |
| Phone photo with a shadow | 17,380 | 17.38 | 16.97 | yes | 2,620 | 0.92 | 1.000 |
Source: our test on 2026-11-10 (harness eacd79c, site code eacd79c), headless Chromium 145 on a desktop Mac, 4 images we made. Similarity is our own 8×8-block luma score (SSIM): 1.000 means no visible change. How we test
Other settings people try
| Setting | Pixels | In range | Under the minimum | Over the maximum | Median file |
|---|---|---|---|---|---|
| Converter, JPG quality 100 | 709 × 236 | 0/4 | 0 | 4 | 50,832 bytes |
| Converter, PNG | 709 × 236 | 0/4 | 0 | 4 | 127,248 bytes |
| Converter, JPG quality 100 | 472 × 236 | 1/4 | 0 | 3 | 32,121 bytes |
| Converter, PNG | 472 × 236 | 0/4 | 0 | 4 | 77,200 bytes |
| Old 12 KB target | 709 × 236 | 4/4 | 0 | 0 | 11,808 bytes |
SSC asks for JPEG or JPG, so the PNG rows are for comparison only. The 12 KB row is an old limit that answers on Q&A sites still quote.
Source: our test on 2026-11-10 (harness eacd79c, site code eacd79c), headless Chromium 145 on a desktop Mac, 4 images we made. How we test
How to prepare the signature
- Sign on plain white paper and scan or photograph it in even light.
- Crop close around the signature to the shape of 6.0 × 2.0 cm, then resize it to 709 × 236 px. That is the centimetre size at 300 DPI.
- Add one JPG, PNG or WebP image above (or a HEIC in Safari). The target is 20 KB. Untick Allow shrinking so the pixels stay.
- Press Compress image. Check the size under the result: at least 10,240 bytes and at most 20,000 bytes.
- Download it and upload it on the SSC form.
When the SSC signature goes wrong
SSC says my signature is under 10 KB.
At 472 × 236 px our thin-pen signature came out at 10,200 bytes: over 10 KB if a KB is 1,000 bytes, under it if a KB is 1,024. We do not know which the portal uses. At 709 × 236 px all 4 styles were in range, so use the larger size. Applicants report the form saying the signature is missing even with the right dimensions (user reports, for example this Quora question). The compressor cannot add bytes.
The result is close to 20 KB. Is it safe?
Yes, if it shows 20,000 bytes or fewer: that is under 20 KB both ways. Our grey scan came out at 19,920 bytes, 80 bytes under. Some answers on Q&A sites suggest aiming lower to be safe (user reports, for example this Quora answer).
My scanned signature looks grey and blotchy.
A grey, noisy scan costs many bytes, so the compressor lowers the quality. Our scan style needed quality 0.78 at 709 × 236 px and scored 0.857, against 1.000 for a clean pen line. At the old 12 KB target that people still quote, the same scan fell to 0.817 (user reports quote that limit, for example this Quora answer). Scan on white paper in good light.
What DPI should I scan at?
The GD notice gives 300 DPI for the signature; the CGL and CHSL notices give only centimetres. At 300 DPI, 6.0 × 2.0 cm is 709 × 236 px.
Is 20 KB the same as 20,480 bytes?
Our compressor counts 1,000 bytes as one KB. None of the official pages above says whether a KB is 1,000 or 1,024 bytes. A target of 20 KB gives at most 20,000 bytes, which is under the cap either way. The minimum is the risk: if the portal counts 1,024 bytes, a 10 KB minimum needs at least 10,240 bytes, so check the size under the result.
The official rules
From the official pages, with the date each one shows. An archived page was not reachable from our test machine, so we read a saved copy.
| Rule | Value | Source | Date |
|---|---|---|---|
| SSC: signature file size | 10-20 KB | SSC Notice: Combined Graduate Level Examination, 2026 | 2026-05-21 |
| SSC: signature file size and dimensions (main text) | 10-20 KB; about 6.0 x 2.0 cm | SSC Notice: Combined Higher Secondary (10+2) Level Examination, 2026 | 2026-09-07 |
| SSC: signature dimensions | about 6.0 x 2.0 (width x height) | SSC Notice: Combined Graduate Level Examination, 2026 | 2026-05-21 |
| SSC: signature dimensions | about 4.0 x 2.0 (width x height) | SSC Notice: Combined Graduate Level Examination, 2026 | 2026-05-21 |
| SSC: signature dimensions (annexure) | about 4.0 x 2.0 (width x height) | SSC Notice: Combined Higher Secondary (10+2) Level Examination, 2026 | 2026-09-07 |
| SSC: signature resolution | 300 DPI | SSC Notice: Constable (GD) ... Examination, 2026 | 2025-12-01 |
| SSC: signature file size and dimensions | 10-20 KB; about 6.0 x 2.0 cm | SSC Notice: Constable (GD) ... Examination, 2026 | 2025-12-01 |
| SSC: signature file size and dimensions | 10-20 KB; about 6.0 x 2.0 cm | SSC Notice: Stenographer Grade 'C' & 'D' Examination, 2026 | 2026-04-24 |
| SSC: signature file size and dimensions | 10-20 KB; about 6.0 x 2.0 cm | SSC Notice: Multi-Tasking (Non-Technical) Staff and Havaldar Examination, 2025 | 2025-06-26 |
The notices give two sizes: about 6.0 × 2.0 cm in the main text and about 4.0 × 2.0 cm in the annexure. At 6.0 × 2.0 cm all 4 of our files were in range, against 3 of 4 at 4.0 × 2.0 cm. SSC takes the photo live in the form, so the signature is the only file to prepare.
Other pages for this job: Compress image to 20 KB · Compress image · Exam photo and signature guide