How to get an image under 20 KB
- Drop or choose your images. The target is already set to 20 KB and the output format to JPG, which reaches small sizes with the least visible damage.
- Pixdesk tries the highest quality first and steps down until the file fits. If quality alone cannot get there, it reduces the width by small steps and tries again. The row tells you what it did, for example “Quality 64% to fit under 100 KB”.
- Drag the preview divider and zoom to 100% to check faces and text, then download the file or a ZIP of the whole batch.
Pixdesk counts 1 KB as 1,000 bytes and always lands below the number, so the file also passes forms that count 1 KB as 1,024 bytes. A 20 KB limit means at most 20,000 bytes here.
Where a 20 KB limit shows up
20 KB is one of the tightest limits you will meet. It is common for scanned signatures, thumb impressions and small ID photos on exam, job and government application portals, and for avatar fields on older forums and intranets. At this size a full-resolution phone photo is out of the question: a 12-megapixel picture is usually 2–5 MB, more than a hundred times too big.
The good news is that the forms that ask for 20 KB rarely need many pixels. A signature is read at a few hundred pixels wide, and a passport-style photo is usually shown at 200–400 px. Shrinking the dimensions is not a failure here; it is what makes the file readable at the size the portal actually displays.
What the sample shows
Our 1600 × 1067 sample photo starts at 499 KB. To get it under 20 KB, Pixdesk first tried quality alone; even at 50% the full-size photo was too large, so it reduced the width step by step and settled on 870 × 580 px at quality 67%: 19.7 KB. That is still sharp on a phone screen. A cropped head-and-shoulders photo or a signature on white paper keeps far more detail at the same size, because flat areas cost almost nothing.
| Step | What Pixdesk did | Result |
|---|---|---|
| 1 | JPG at the highest quality that fits, full size | too large at 1600 px wide |
| 2 | Reduce the width in steps, estimating each step from the size | 870 × 580 px |
| 3 | Search quality again at the new size | 67% → 19.7 KB |
Tips for a better small file
- Crop first. Remove background and empty space before compressing; every pixel you cut is a pixel you do not pay for. Resize to the dimensions the form asks for (for example 140 × 60 for a signature) with the resizer.
- Scan signatures on plain white paper in good light. Shadows and paper texture are expensive detail.
- Use JPG, not PNG, for photos. PNG cannot reach 20 KB for a photo without reducing it to very few colors.
- Check the text and faces at 100% with the preview zoom. If the form shows the image small, a slightly soft file is fine.
Frequently asked questions
Can any photo be compressed to 20 KB?
Yes, but large photos will be reduced in size to get there. Pixdesk keeps quality at 50% or higher and shrinks the width instead, because a smaller sharp image looks better than a full-size blocky one.
Will my image be exactly 20 KB?
It will be at or below 20,000 bytes, usually within a few percent of the limit. Pixdesk picks the highest quality that fits rather than landing on an exact byte count.
What size in pixels fits in 20 KB?
It depends on the content. Our grainy sample photo fit at 870 by 580 pixels. A signature on white paper or a plain-background portrait can stay much larger.
Should I use JPG or PNG for a 20 KB signature?
JPG is the safe choice and is accepted almost everywhere. A PNG signature with only black ink on white can also be tiny with Smart PNG mode, but check that the form accepts PNG.
Can I compress several signatures and photos at once?
Yes. Drop up to 30 files. Each one is compressed to the same 20 KB target and you can download them separately or as a ZIP.
Is it safe to compress ID photos and signatures here?
The files never leave your device. Processing happens in your browser tab and Pixdesk has no upload server. The new files also contain no EXIF metadata.
Why does the form still reject my 19 KB file?
Most portals also check the pixel dimensions or the file type. Resize to the exact width and height they ask for, keep JPG, and make sure the file name ends in .jpg.
Does it work with iPhone HEIC photos?
Yes. HEIC photos are decoded in the browser and saved as JPG under 20 KB, which is the format most application forms expect.
Sources
- Chrome for Developers: Lighthouse “Efficiently encode images” — estimates savings by re-encoding JPEGs at quality 85
- Google for Developers: An image format for the Web (WebP) — lossy WebP 25–34% smaller than comparable JPEG; lossless WebP 26% smaller than PNG
Sources checked on 19 October 2026.