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FitKB

Signature

Signature Resize to 20KB Online

Online applications often ask for a scanned signature in a wide box under 20 KB. FitKB fits your signature photo into a 400×160 pixel white canvas without cropping it, then compresses it under the limit.

Your photo

Original: —

Result

The compressed photo appears here. The Download button below turns on when it is ready.

New size
—
Exact
—
Limit
20,000 bytes
Dimensions
—
Quality
—
Saved
—
Settings
KB
px
px
50 %

0 keeps the top of the photo, 100 keeps the bottom. Used when cropping.

How to use the Signature Resize to 20KB

  1. Photograph your signature

    Sign with a black or dark blue pen on plain white paper. Photograph it from directly above in good light, filling most of the frame.

  2. Upload it

    Choose the photo. FitKB places the whole signature inside a 400×160 pixel white box without cropping any part of it.

  3. Change the box if your form needs it

    Enter the width and height your form specifies. The signature is centred and padded with white.

  4. Download

    Check that the strokes are readable in the preview, then tap Download.

Output specification

These are the starting settings for this page. You can change every one of them in the Settings panel above.

Signature Resize to 20KB output specification
Canvas400 × 160 px, white padding
Size limit20 KB by default, adjustable
FitWhole signature kept, never cropped
Output formatJPEG
TipSign with a dark pen on plain white paper

Methodology, privacy and accuracy

  • Runs on your device. The photo is decoded and re-encoded with the browser's Canvas API. It is never uploaded, so passport photos and signatures stay private.
  • How the size is reached. FitKB tries the highest JPEG quality first, then binary-searches the quality until the file is at or under the limit. Dimensions are reduced only when quality alone cannot reach it, and never for fixed-size photos.
  • Safe for strict forms. The limit is applied as KB × 1000 bytes, so the file passes whether a portal counts 1 KB as 1000 or 1024 bytes. Metadata such as GPS location is not copied into the new file.
  • Tested. The size search and crop calculations are covered by automated tests.
  • Last reviewed: .

Frequently asked questions

Why is there white space around my signature?

Contain mode keeps the entire signature and fills the rest of the box with white, so nothing is cut off. Crop the photo closer to the signature before uploading to reduce the padding.

The paper looks grey. Can I fix that?

Retake the photo in brighter, even light, or near a window. Grey paper costs bytes, while a clean white background compresses to almost nothing.

Are my photos uploaded to a server?

No. The photo is decoded, resized and compressed inside your browser with the Canvas API. Nothing is uploaded, so ID photos and signatures never leave your phone or computer.

Why is the result a little under the KB limit instead of exactly on it?

Upload forms reject files that are even one byte over the limit, and some count 1 KB as 1000 bytes while others use 1024. FitKB stays at or under the limit times 1000 bytes, which passes both checks, and picks the highest quality that fits.

Can I use photos from an iPhone (HEIC)?

Yes in Safari, and when you pick a photo through the iPhone photo picker it is usually converted to JPG automatically. If another browser cannot open a HEIC file, export it as JPG (Share, then Save as JPEG) and try again.

Learn more

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