How to Compress a Signature Image to 20 kB for Online Forms

To make a signature image under 20 kB, start with a sharp signature on plain paper, crop away most of the unused paper, export it as JPG if the form requires JPG, and compress it to the form’s limit. Then check the downloaded file: its size, dimensions, format and legibility all matter. If the form says 10–20 kB, a 7 kB result is too small even though it is under 20 kB.

This is a guide for a picture of a handwritten signature. A cryptographic signature inside a PDF is different; rewriting a signed PDF can affect its validation. See our PDF text and signature checks for that case.

Read the signature field before editing

Write down four things from the current application: accepted file format, minimum and maximum file size, required pixel dimensions or physical size, and any ink or background rule. Do not copy a preset from a different exam. Our government form requirements guide shows how much these rules vary between portals.

For a concrete example, the SSC Combined Hindi Translators 2026 notice specifies a JPEG/JPG signature of 10–20 KB, about 6 × 2 cm, and warns against blurred or miniature signatures. It does not state one exact pixel grid in that instruction. SBI’s careers FAQ also gives 10–20 KB but prefers 140 × 60 pixels. Those are examples, not a universal signature size. Your live application instructions take priority.

Capture a clean signature

1. Sign on plain white paper with the ink specified by the application. Use a normal, complete signature that resembles the one you will use later.
2. Photograph it in even light or scan it. Keep the camera parallel to the paper so the letters do not taper. Check the original for focus and shadows before you edit.
3. Crop around the full signature, leaving a small white margin. Keep every dot, flourish and thin stroke. Do not include most of the sheet or the desk.

The MSTC upload instructions similarly advise cropping before resizing and specify black ink on white paper for their form. That preparation usually matters more than repeatedly saving a poor original at lower quality. Compression cannot bring back a faint or out-of-focus stroke.

Resize and compress it to the form’s limit

1. Open the 20 kB image compressor and select your cropped signature image. Processing takes place in your browser.
2. Set the target below the form’s maximum. For a 10–20 kB range, 18 kB leaves some room below the upper boundary; it is a starting point, not a promise that the output will clear the 10 kB minimum.
3. Under Format & dimensions, choose JPG / JPEG when the form requires it. If the form specifies exact pixels, choose Exact width × height and enter them. This mode crops edges to fit a different aspect ratio, so inspect the result for missing strokes. If the dimensions are only preferred or approximate, avoid forcing a crop that harms the signature.
4. Compress and review the preview. Download only when the entire signature is clear. The tool may return an already-small original unchanged, so verify its format and dimensions too.

If your source is a PNG, simply changing .png to .jpg in its filename will not convert it. Selecting JPG output creates a JPG when the tool produces a new result. If the tool returns the original unchanged, use an image editor to export a real JPG and check the saved file.

Check the downloaded file, not just the preview

Open the saved image and confirm:

• Size: inside the form’s whole range, including the minimum. Inspect the actual file size rather than relying on a rounded label.
• Format: JPG/JPEG if required. A renamed PNG is still a PNG.
• Dimensions: the exact width and height if the form mandates them. A centimetre measurement alone is not an exact pixel instruction.
• Clarity: no cropped stroke, blurred letter, heavy JPEG blocks, gray shadows or writing so small that it disappears at normal viewing size.

If the image is below a stated minimum, compressing it further cannot help. Try the sharper original, a less aggressive export or a fresh scan at the permitted dimensions. The compressor is designed to stay below a target; it does not pad a file merely to reach a minimum. If the upload still fails despite the right size, use our upload rejection checklist to check format, dimensions and the file actually selected.

On a phone, open the downloaded image from the Files or Downloads app rather than judging the small thumbnail in the browser. Make sure the upload picker selects this new file, not the original photo with a similar name.

Common mistakes that cause rejection

The signature is cut off. Exact width and height can crop the edges when the source shape differs from the requested shape. Re-crop and position the signature with more space around every stroke before using exact dimensions.

The file is under 20 kB but too small. A 10–20 kB field has two boundaries. Verify the lower one on the final download. Do not assume any under-20-kB tool can make a file meet a minimum.

The result looks gray or faint. Start again from a better lit photo with dark ink. Repeated JPEG exports can make fine strokes worse. Keep the original as your master copy.

The form asks for another size. Use its actual range. A 20 kB ceiling from one recruitment does not apply to every government form. When the form provides both centimetres and pixels, follow its stated pixels rather than a general conversion table.