Shrink a photo to an exact file-size limit — 20 KB, 50 KB, 100 KB or whatever an upload form demands. The tool finds the best quality that fits, right in your browser. Nothing is uploaded.
🔒 This tool runs entirely in your browser. Nothing you enter or upload is sent to our servers.
How to use the Compress Image to KB
- Choose the size limit the form gives you, such as 50 KB, or pick Custom and type your own.
- Drop in one or more photos. Each is compressed immediately on your device.
- Check the result: the final size, the dimensions and the quality used are shown next to a preview.
- Download the file and upload it to your form.
About this tool
Exam portals, visa applications, job sites and government forms often refuse a photo above a fixed size — 20 KB, 50 KB, 100 KB — and leave you to guess how to get there. A general compressor makes you nudge a quality slider until the number happens to fit. This tool takes the limit itself and works backwards to the best-looking file that stays under it.
It first searches for the highest JPEG quality that fits while keeping every pixel. Only when the limit is too tight for a decent-looking result at full size — a 12-megapixel phone photo squeezed into 20 KB, say — does it reduce the dimensions as well, choosing the largest size that still fits and then raising the quality as far as the limit allows. The result lands just under your target rather than far below it, so you keep as much detail as the form permits.
Forms rarely say whether a kilobyte means 1,000 or 1,024 bytes, so the tool treats 1 KB as 1,000 bytes: a file under that is under the limit by either definition. Re-encoding also strips the photo’s hidden metadata, such as the GPS location and camera details, which is no bad thing when you’re sending it to a stranger’s server. Everything happens on your device; the photo is never uploaded here.
Frequently asked questions
How do I compress a photo to 50 KB?
Choose 50 KB as the target size and drop the photo in. The tool returns the largest, best-quality JPEG it can make that is still under 50 KB, and shows you the final size before you download it.
Will the file be exactly 50 KB?
No — just under it, which is what an upload form checks for. Hitting a size to the exact byte isn’t possible with JPEG, and a file one byte over the limit would be rejected.
Is 1 KB 1,000 bytes or 1,024 bytes?
Forms use both. This tool counts 1 KB as 1,000 bytes, so the result is under your limit whichever definition the form uses.
Why did the image dimensions get smaller?
Below a certain quality a JPEG starts to look blocky, so the tool won’t go lower than that. When the limit is too tight for the full-size photo — very common for 20 KB or 50 KB limits — it reduces the pixel dimensions instead, which looks much better than extreme compression.
The form also needs exact dimensions, like 200×230 pixels or 3.5×4.5 cm. What do I do?
Get the dimensions right first with the Image Resizer or the Passport Photo Maker, then bring the result here to bring it under the size limit.
Can I compress an iPhone HEIC photo?
Most browsers can’t open HEIC files. Convert it first with the HEIC to JPG converter, then compress the JPG here.
Is my photo uploaded?
No. It is read, compressed and handed back by your own browser. Nothing is sent to a server.