Compress Image to 20KB
Some forms only accept signatures and thumbnails under 20 KB. Choose your image and this tool finds the best quality that fits, reducing the dimensions only as far as needed.
Runs in your browser. Your data is not uploaded.How our tools work
No image to hand? (CC0)
Large photos have more pixels than fit in 20 KB. The width and height are reduced only as far as needed, keeping the aspect ratio, instead of lowering quality until the image looks blocky.
Advanced settings: format and metadata
Accepted by almost every upload form. Transparent areas are filled with white.
Metadata
Compressed images are saved without metadata such as camera details and GPS location, which also saves bytes. If your image is already under 20 KB, it is returned unchanged, metadata included.
Several images, or a different size limit? Use Target size in the image compressor.
How do I compress an image to 20KB?
Choose the image and the tool finds the highest quality that fits in 20,000 bytes, reducing the dimensions only when quality would drop below 70%. A signature or small portrait usually fits easily; a full phone photo ends up a few hundred pixels wide. You see the exact size in bytes before downloading the JPG.
- Crop the image to what the form needs, such as your face or the signature, so no bytes are spent on background.
- Select or drop the image. Leave “Reduce dimensions if needed to keep good quality” on unless the form sets exact pixel dimensions.
- Check the preview, the exact size in bytes and the final dimensions. Zoom in to make sure text and faces are still clear.
Key features
Built for signatures and thumbnails
Strict 20 KB limits are usually for a signature or a small ID photo, and both fit at good quality once they are cropped to what matters.
Keeps a set pixel size
Turn off “Reduce dimensions if needed” to keep the size a form specifies; only the quality changes, and the tool tells you if 20 KB can’t be reached that way.
Common uses
- Signatures for exam, university and government application forms
- Thumbnail photos for ID cards and membership systems
- Small profile images for portals with strict upload limits
Supported formats and limits
- Input
- JPG, PNG, WebP, GIF, BMP, AVIF up to 40 MB. HEIC where your browser supports it
- Output
- JPG, 20,000 bytes or smaller. WebP where your browser can save it (not Safari)
- Quality
- 70% or higher while dimensions may be reduced; down to 40% if you keep the dimensions
What a 20 KB result looks like
In Chrome, a 12-megapixel photo taken on an iPhone 14 (4032 × 3024 pixels, 3.7 MB) came out at 19,689 bytes (19.7 KB), reduced to 373 × 279 pixels at 75% quality. A detailed photo has to shrink that far.
What fits in 20 KB?
20 KB is 1% or less of a typical phone photo, so most of the pixels have to go. A tightly cropped signature in dark ink on white paper fits easily at high quality, because plain paper compresses to almost nothing. A portrait photo fits at a few hundred pixels wide, which is enough for the small preview most forms show.
If the form also gives pixel dimensions, such as 140 × 60 for a signature, the signature resizer sets them exactly and keeps the file under the limit in one step.
Why not the Image Compressor’s Target size?
The Image Compressor can aim at 20 KB too, under Target size › Custom, and takes up to 20 images at once. But it keeps the original dimensions unless you tick “Allow smaller dimensions if needed”, and at full size a phone photo can’t get near 20 KB: our 4032 × 3024 test photo was still 1.03 MB at 40%, the lowest quality it tries. This page takes one image, aims at 20,000 bytes and reduces the dimensions as soon as quality would drop below 70%, which is what a signature or ID thumbnail needs.
Related tools
Frequently Asked Questions
Why does my 20 KB image look small?
A photo with millions of pixels can’t fit in 20,000 bytes without heavy blocking, so the tool reduces the dimensions instead of the quality. For a sharper result, crop the image tightly before compressing, so the pixels go to the part that matters.
My signature is under 20 KB but the form still rejects it. Why?
Forms often check more than the file size: the pixel dimensions (such as 140 × 60), the format (usually JPG), or a minimum size such as 10 KB. Check the form’s full requirements. The Signature Resizer sets exact pixels and a KB limit together.
Is 20 KB the same as 20,480 bytes?
Only on sites that count 1 KB as 1,024 bytes. Others use 1,000. The tool stays at or under 20,000 bytes, so the file passes either way.
Sources
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