Quick answer: A 20 KB limit is common for small uploads such as signatures and thumbnails. Add your image, keep 20 KB selected and download a JPEG that fits. Open the optimizer with 20 KB selected — your image stays on your device.
How to compress an image to 20 KB
- Open the Exact Image KB Optimizer; 20 KB is already selected.
- Add your image: choose, drag or paste a JPG, PNG or WebP file (or several).
- Press Compress to 20 KB. The tool tries the highest quality first and measures every result.
- Check the result — size, dimensions, format and a before/after comparison — then download it.
What fits in 20 KB
20 KB is twice the room of 10 KB, so photos stay noticeably larger and sharper.
| Image | Result at 20 KB |
|---|---|
| Detailed 12-megapixel photo (4000 × 3000 px) | 527 × 395 px, JPEG |
| Simple graphic with text (1600 × 900 px) | 756 × 425 px, JPEG |
Measured with the optimizer in Chrome in October 2026. Your results depend on the image: smooth or simple images keep more pixels than busy, detailed ones.
Is 20 KB counted as 20,000 or 20,480 bytes?
Both conventions are in use: some sites count 1 KB as 1,000 bytes, others as 1,024. The optimizer aims under the stricter 20,000 bytes, so the result passes either way. The target is a maximum: the file will be at or below 20 KB, usually just under it.
Getting a good result at a very small size
- Crop to what matters first — a signature, a face or a logo — before compressing; every pixel you remove leaves more room for quality.
- Use JPEG. PNG is lossless and usually has to shrink a lot to reach a target this small.
- For scanned signatures, a clean scan on white paper compresses far better than a photo of a page.
- Expect small dimensions: a few hundred pixels across is normal for a photo at this size.
If the target cannot be reached
Very detailed or noisy images may not fit even at small dimensions. The optimizer then tells you the smallest size it could reach instead of producing a broken file. Cropping the image, or choosing a slightly larger target if the form allows it, usually solves this.
Frequently asked questions
How do I reduce a photo to under 20 KB?
Open the optimizer with 20 KB selected, add the photo and press Compress. It keeps the highest quality that fits and reduces the dimensions only when needed.
How big will a 20 KB photo be?
In our test a detailed 12-megapixel photo came out at 527 × 395 px. Simpler images keep more pixels.
Why is my signature still over 20 KB?
Photos of paper pick up shadows and texture. Scan on white, crop tightly and save as JPEG; it then compresses easily.
Will the file be exactly 20 KB?
It will be at or below 20 KB, usually just under — a maximum is what upload limits check.
Related
- Exact Image KB Optimizer (20 KB selected)
- Compress an image to 10 KB
- Compress an image to 30 KB
- Compress an image to 50 KB
- Image Requirements Checker — check a file against size, shape and format rules
- Social media image sizes