Some upload boxes are strict. An online application form for a job, an exam or a government service may ask for a scanned signature and a small photo, each under 20 KB, and refuse anything bigger. A phone photo is often a hundred times that size or more.
This page is set up to resize an image to 20 KB, which here means its file size, not its shape. Target size is already set to 20 KB, so you open the picture, check the result and save. The tool finds the best quality that fits, and if the picture is too detailed to fit at any quality, it makes it smaller in pixels too. It runs in your browser, so your signature or photo is never uploaded.
Where a 20 KB limit comes up
A cap this tight is most common on forms that collect files from many applicants. Typical places include:
- An online application form for an exam, a course, a job or a permit, asking for a scanned signature.
- The same forms asking for a small passport-style photo, sometimes with a separate limit.
- Older portals and intranets that set one small limit for every picture.
- Badges and small avatars on systems that only show pictures at a small size.
Read the form's rules before you start. Many give a file size, some give a range such as 10 KB to 20 KB, and some also give a size in pixels or a format, usually JPG. This page handles the file size; the tips below cover the rest.
How to compress an image to 20 KB
- Press Select images and choose the photo or the scan. A phone photo, including an iPhone HEIC photo, opens too.
- Check that Compress by shows Target size and the slider reads 20 KB.
- Leave Allow a smaller picture size on, so the tool can reduce the pixels if it must.
- Under Format, pick JPG if the form asks for JPG. To compress a JPG to 20 KB, keep Original: a JPG stays a JPG.
- Read the Result line: it gives the format, the size in pixels and the exact file size, such as JPG · 640 × 480 · 19 KB · 99% smaller.
- Press Compress and save. The file name ends in _compressed.
Doing a photo and a signature for the same form? Select both together, and each gets the same 20 KB target. If the photo has a bigger limit, such as 50 KB, do it on its own with a different target. The Shortcuts on this page jump straight to the other sizes.
What happens to your picture at 20 KB
20 KB is small enough that the picture has to give something up. The tool works in this order, and stops at the first step that fits:
- It tries up to 8 quality levels between 20 and 95, at the picture's full size, and keeps the highest one that comes in under 20 KB.
- If even quality 20 is too big, and Allow a smaller picture size is on, it shrinks the picture in pixels and searches again.
- It can do that in up to 3 rounds, but never shrinks the picture below a quarter of its width and height.
So a plain scan of a signature usually fits at full size, while a detailed photo comes out smaller in pixels. A very large photo can miss the target even at a quarter of its sides. If that happens, switch on Also make it smaller in pixels and set a small Longest side, such as 640, so the search starts from a smaller picture. The split view and the Result line show exactly what you will get before you press Compress.
How hard it is to compress an image to 20 KB depends on the picture more than on its size in pixels. A scan of a typed page or a signature is easy. A busy street photo, full of edges and texture, is the hardest case, and it is the one that ends up smallest in pixels.
If no setting fits, Compress is blocked and the panel tells you why: No setting gets this picture under 20 KB, even made smaller. Switch on Also make it smaller in pixels, or pick a bigger target. With Allow a smaller picture size switched off, it suggests switching that on too.
Tips for a signature or photo under 20 KB
Getting a signature under 20 KB is rarely hard, because ink on paper is mostly plain white. A photo under 20 KB takes more care, because faces, hair and backgrounds are full of fine detail. The less there is in the picture, the more quality the tool can spend on what matters, so a few minutes of preparation give a much cleaner result.
- Sign in dark ink on plain white paper, and photograph or scan it in good, even light without shadows.
- Cut away the empty paper around a signature with Crop image. A tight crop leaves fewer pixels to store.
- If the form gives a size in pixels, such as 300 × 80 for a signature, set it with Resize image first, then bring the result here.
- A signature in grey tones often compresses better than one with a coloured tint from the paper. Black and white image removes the colour.
- For a photo, crop to the head and shoulders and use a plain background.
20 KB, 20 KiB and the form's own rules
Sizes are counted in two ways, and forms do not always say which. Here a KB is 1,000 bytes, as the site writes sizes everywhere, so a result under 20 KB passes either way.
| Counted as | 20 KB is | A result from this page |
|---|---|---|
| 1,000 bytes per KB (this site) | 20,000 bytes | At or under 20,000 bytes |
| 1,024 bytes per KB (some forms) | 20,480 bytes | Under the limit, with room to spare |
The result usually lands close to the target, a little under it, so a form that asks for 10 KB to 20 KB is normally happy too. Check the Result line before you save. Your computer may show the file as 19 KB or 20 KB, because file managers round in their own way.
Get your picture under 20 KB now
To compress an image to 20 KB, crop it tight, resize it first if the form gives a size in pixels, and let Target size find the best quality that fits. The Result line tells you the exact size before you save. A signature under 20 KB usually keeps its full size; a photo may come out smaller in pixels.
Select your photo or signature above and press Compress. For other limits, the full image compressor takes any target from 10 KB.
