20 KB is a signature size, not a portrait size
Search results for “compress image to 20kb” are full of people crushing passport photos until the face is a smear. Most 20 KB rules are for signatures. A black pen on white paper is almost binary data — JPEG can store it in well under 20 KB at a readable size. A color selfie cannot. If a portal asked for a photograph at 20 KB, treat that as an exception and expect softness.
ExactKB still lets you force a portrait to 20 KB because a few university and state forms really do print that number. The encoder will drop quality, then pixels. That is not a defect. Twenty kilobytes is a small container. Use the Signature 20 KB preset when you have ink on paper. Use 50 KB or 100 KB for faces.
How to photograph a signature that survives 20 KB
Most 20 KB failures are bad source files, not a weak encoder. People photograph a signature on ruled notebook paper, under yellow tube light, at an angle, then screenshot the gallery thumbnail. JPEG then spends its budget on the lines and the noise.
- Sign with a black or very dark blue ballpoint on unlined white paper. Avoid gel glitter and fountain-pen bleed.
- Place the paper on a table. Shoot from directly above. Fill the frame with the signature plus a small margin — do not include the whole A4 sheet.
- Turn off the decorative filter. If the phone saved HEIC, drop it here anyway; conversion happens locally.
- Crop in any editor so only the signature remains. Then set this page’s 20 KB target and JPG output.
- If the result is still over, set longest side to 600 px and run again. A signature does not need 4000 px.
Thumb impressions follow the same logic: high contrast, tight crop, white (or very light) field, JPEG out. Do not upload a color scan of a full police form.
What 20 KB looks like in bytes
ExactKB’s default kilobyte is 1024 bytes, so 20 KB is 20,480 bytes. Some portals treat 20 KB as 20,000 bytes. If you are rejected at “20.1 KB” in their UI, uncheck the 1024-byte option and compress again. We do not pad the file to a theatrical 20,000.0. The download will sit at or under the ceiling you chose.
After you download, confirm the size in the operating system — not in a chat app that recompresses attachments. WhatsApp and some email clients will re-encode a signature and can push a 19 KB JPEG back over the cap, or convert it to a sticker-like image the portal then rejects as the wrong type.
When 20 KB is the wrong tool
If the field says “photograph 20–50 KB,” start at 50 KB and only drop if the portal’s preview looks fine and the notice prefers the floor. If the field says “photograph 100 KB,” do not use this page to over-crush. You will spend time cleaning artifacts that a 100 KB budget would have avoided. If you have an iPhone HEIC of a face, convert it on HEIC to JPG with a 50 or 100 KB target, not 20.
ExactKB is not a handwriting OCR service and not a bank. A 20 KB file that looks acceptable on your phone can still fail a human checker if the ink is faint or the crop cuts the last letter. Size is necessary, not sufficient.
Where a 20 KB limit shows up
| Form or portal | Typical limit | Notes |
|---|---|---|
| Exam signature (SSC, RRB, many state PSCs) | 10–20 KB | JPEG, high contrast, white background |
| PAN / KYC signature | 4–20 KB | Varies by NSDL vs UTIITSL window |
| Some university admission photos | 20 KB | Rare for portraits; confirm the brochure |
| Thumb impression uploads | 10–20 KB | Crop tightly before compressing |
How to hit 20 KB
- Choose the photo on this page. It stays in this browser tab.
- Confirm the 20 KB target (already selected on this page).
- Leave output as JPG unless the form explicitly wants WebP or PNG.
- If the file is still over after a quality search, set a longest-side cap (1000 or 600 px) and run again.
- Download the file and check the size in your file manager before you submit.
Questions about 20 KB
Why do signature fields cap at 20 KB?
A signature on white paper compresses extremely well. Portals keep the cap low so every application stays a few kilobytes. A phone photo of a signature is usually hundreds of kilobytes until you JPEG it hard or shrink the longest side.
Will 20 KB destroy a face photo?
A full-resolution portrait at 20 KB will look crunchy. For photos, prefer 50 or 100 KB. Use 20 KB for signatures, thumb impressions, and tiny “upload your initial” fields.
What if the encoder still cannot fit 20 KB?
Set longest side to 600 px and keep JPG output. If it still fails, the source may be a screenshot with text — crop to the signature only, then retry.