Compress a JPEG to 100 KB (or any other exact size)
A form asks for “image under 100 KB”. Your phone photo is 4 MB. You open a free online compressor, drag the photo in, and discover that the only controls on offer are a quality slider that says “compress by 70%”. 70% of 4 MB is still 1.2 MB. The slider does not solve the problem, because the problem is not a percentage — it is a number. This page is for the next two minutes of your life, which are about getting under that number.
The fastest way: an exact target
Compress to exactly 100 KB Compress to 240 KB Compress to 50 KB
Each button opens the compressor with the exact-size mode already on and that number already entered, so you can skip straight to dropping the file in.
Open the image compressor, drop your JPEG in, and let it run — the tick and the number are already done for you. The tool does a binary search through the quality range: try a mid value, see if the result is too big or too small, halve the range, try again. After about eight attempts it lands within a couple of percent of your target, and the whole thing happens in well under a second. The output is the highest-quality JPEG that still fits under 100 KB.
Everything is local: the file never leaves your browser, you can confirm by going offline mid-compression.
If a percentage is all you have
Some form instructions do not give you a target — they say “compress the image” and hope. Three rules that work in 90% of cases, in order of how much they save:
- Resize first. A 4000-pixel-wide photo shown in a 300-pixel form field wastes 90% of its bytes. Resize to about 1200 pixels wide before compressing; you will lose nothing the reviewer can see.
- Convert PNG to JPG. If the file is a screenshot, this alone often drops it below 100 KB with no other change. The trade-off is loss of transparency, which screenshots rarely need.
- Reduce quality to 70–80. For a 1200-pixel-wide JPG, this usually lands at 80–200 KB. Combine with step 1 if you are still over.
For the deep explanation of why percentage-based compression fails this kind of task, see the original compress-to-an-exact-size guide in the tutorials section.
Different targets, different starting points
| Target size | What usually works | When the photo is a |
|---|---|---|
| 200 KB | Quality 70–80, keep full resolution | Form upload, social post, email signature |
| 100 KB | Resize to ~1600 px wide, quality 70 | Generic form field, application portal |
| 50 KB | Resize to ~1000 px wide, quality 60–70 | Tight form, exam portal, signature image |
| 20 KB | Resize to ~600 px wide, quality 55–65 | Passport-style, ID upload, very small avatar |
These are starting points — a plain wall compresses far more aggressively than a forest, because detail is what costs bytes. The exact-size mode on the compressor handles the adjustment automatically.
Common reasons a “compressed” file is still over the limit
- The form wanted JPG, the file is PNG. Convert first, then compress — the converter keeps the workflow local.
- The limit is in MB, not KB. 100 KB and 100 MB differ by a factor of a thousand, and the mistake is easy to make.
- EXIF metadata pushes you over. A 95 KB image with several megabytes of camera metadata will still fail some upload checks. The compressor has a strip-EXIF option for exactly this case.
- The dimensions are off. The form wanted 200×230 and you sent 4000×3000. Use the resizer for this — resize first, compress second.
Frequently asked questions
Will compressing to 100 KB make the photo look bad?
For a 1600-pixel-wide photo, no — you can usually stay at quality 70–75 and look indistinguishable from the original at 100% zoom. Below quality 60 artefacts start to appear in smooth areas (skies, skin) and below 50 they become obvious.
Can I get exactly 100.0 KB?
Within a few percent. Image encoders are not perfectly predictable, so a tool that promises an exact byte count is either padding the file with garbage bytes or rounding up. The compressor aims for the highest quality that fits under the target, which is what most forms actually want.
Is my photo uploaded?
No. The whole pipeline — resize, convert, compress — runs inside the browser using JavaScript and the HTML canvas element. You can confirm by opening the network tab in developer tools, dropping a file in, and watching the “no image data left the page” result. Or just turn off Wi-Fi and try again.
What if I need to hit a target across many photos at once?
Drop them all into the compressor at once. The exact-size mode runs the same search per file, and you get back a single ZIP containing the results.