Why exam forms demand exactly 20KB
Portals don't round in your favor. 'Maximum 20KB' means the file must be 20,480 bytes or less — a 21KB file fails validation instantly, no matter how good the photo looks.
Why so strict? Storage economics. A single exam cycle can draw hundreds of thousands of applicants, each submitting a photo plus a signature. At a few megabytes per file, that's terabytes of storage and slow uploads on low-bandwidth connections. At ~20KB per image, the same data fits in a fraction of the space and uploads in seconds even on weak mobile data. The cap isn't arbitrary — it's infrastructure.
Read your form before you compress
The most common mistake is compressing first and reading the requirements later. Every form specifies up to three numbers, and you need all of them before you start.
**The three numbers that matter.** The KB cap — the maximum file size (e.g., 20KB). Sometimes it's a range (e.g., 10–20KB), which also sets a minimum. The pixel dimensions — required width × height, sometimes a range or an exact figure; bytes and pixels are checked independently. The format — almost always JPG/JPEG for photos and signatures; a perfect 19KB WebP still fails a JPG-only form. Get all three from your form's instructions or the upload page itself before compressing anything.
**Pakistan exam specs: FPSC, PPSC, NTS, CSS.** Pakistani exam portals — FPSC, PPSC, NTS, and CSS applications — commonly specify photo and signature uploads with caps in the tens of kilobytes (photos often around the 20KB mark, signatures lower), plus required pixel dimensions and JPG format. But the exact numbers differ between advertisements and change over time, so treat any specific figure you see quoted online as a starting point only. Always confirm against your advertisement's notification or the upload-page instructions — compress to the numbers on your form, not someone else's blog post.
Photo vs signature at 20KB
Not all images are equally compressible, and this matters enormously at 20KB.
If your form needs both, compress them separately: the signature will need far less compression than the photo.
- Signatures are easy. Black ink on a white background is mostly flat white space, which compresses extremely well. Hitting 20KB (or even 10KB) with a clean signature scan is trivial — you'll barely touch the quality slider.
- Photos need care. A face needs a tight head-and-shoulders crop at 20KB. The crop concentrates your byte budget on the face, keeping it recognizable. A full-scene or full-body photo at 20KB will smear — the bytes spread too thin.
Step-by-step: compress to 20KB
- Step 1 — Crop first. Tight head-and-shoulders for photos; trim excess white space around signatures. Fewer pixels means more bytes per pixel, which means a sharper result.
- Step 2 — Upload. Open https://all-done.xyz/tools/image-compressor and upload the cropped image. Processing happens entirely in your browser — your ID photo never leaves your device.
- Step 3 — Set quality, compress, check. Set the quality slider, click Compress All, and check the compressed-size readout. Still over 20KB? Lower the slider and re-run until it dips just under 20KB — aim for roughly 18–19KB to leave a safety margin against portals that measure strictly.
- Step 4 — Verify the bytes yourself. Download the file and check: right-click → Properties (Windows) or Get Info (Mac). Confirm three things: size at or under 20,480 bytes, dimensions matching your form's requirement, format JPG.
- Step 5 — Upload to the portal and check its preview. If the portal shows a preview, confirm the face or signature is clear and recognizable before submitting.
Rejected? The 5-point checklist
- Bytes vs KB rounding. '20KB' on a portal means 20,480 bytes (20 × 1,024), not 20,000. A file your computer casually calls '20KB' might actually be 20.4KB and fail. Check the exact byte count.
- Pixel dimensions. The portal checks dimensions independently of file size. A 19KB file at the wrong resolution still fails.
- Format must be JPG. Not WebP, not PNG — even if the size is perfect, the wrong format gets rejected.
- Minimum-size rules in ranges. A '10KB to 20KB' specification rejects an 8KB file too. If your form gives a range, aim for the middle.
- Re-compress from the original. If you've run the same file through compression several times, quality and metadata can drift. Start over from the original photo or scan.
Privacy: your ID photo never leaves your device
An exam photo is an identity document — it deserves the same caution as a passport scan. Many free compressors upload your file to their servers for processing, where it's stored, logged, or handled under privacy policies nobody reads.
All Done's image compressor works differently: it processes your photo 100% inside your browser, using your own device's processing power. The file is never uploaded, never stored, never seen by anyone. For ID photos and signatures, that architectural difference is the whole point — there's nothing to leak, because nothing ever leaves.
