How do I get a photo under 100 KB?
Lower the quality slider in small steps and watch the measured output size in the results table until it drops below 100 KB. If you have to go below about 50 to get there, shrink the width first and then compress at a normal quality instead.
Why there is no 'target size' box
The compressor has a quality slider from 1 to 100, not a field where you type the size you want. Every time you move the slider, the image is re-encoded and the table shows the real byte count, not an estimate. The output size cannot be known in advance: two photos at the same quality can end up very different because one is full of detail and the other sits on a plain background, and because they may not have the same number of pixels.
A real test, with numbers
A 1600×1200 product photo of 689.5 KB, compressed in Chrome on a computer:
At quality 80 it came out at 250.9 KB, nowhere near the target.
At quality 50 it was 108.6 KB, still above 100.
At quality 40 it dropped to 85.6 KB, but that is a low setting whose flaws can show when the photo is zoomed.
After reducing the width to 1000 pixels (the height follows to 750 with the ratio locked) and compressing at quality 80: 87.4 KB, 87.3% smaller than the original.
The lesson: when the target is small compared with the photo's dimensions, the extra pixels are the problem, not the quality setting. Resizing and then compressing at a sensible quality gives you a smaller file and a cleaner picture than crushing the quality alone. Another browser may produce slightly different sizes, so always go by the figure the tool shows you.
Step by step
- Open the Image compressor, pick the photo, and choose JPEG as the output if the site you are uploading to does not accept WebP.
- Start at quality 80 and read the Output column in the table.
- Lower the quality in steps of 5 and check the size after each step.
- If you reach about 50 and it is still too heavy, open the Image resizer, reduce the width and choose PNG as its output so this in-between step loses nothing, then bring the new image back to the compressor.
- Once the size is comfortably under the target, look at the preview to make sure the photo still looks acceptable, then download it.
Watch what 'KB' means
The tool counts a kilobyte as 1024 bytes, so 100 KB on screen means 102,400 bytes. Some websites count a kilobyte as 1000 bytes, which makes their limit 100,000 bytes. So do not stop at exactly 99 KB; aim for around 90 KB and you are safe either way. In the test above, a width of 1200 pixels at quality 75 gave 100.4 KB, which is over the line by both counts, and that small excess is enough to get a file rejected.
Common questions
Does compressing change the photo's dimensions?
No. The compressor keeps the width and height as they are, and shows them under each file name. To change dimensions, use the Image resizer.
Can I bring several photos under 100 KB in one go?
You can compress them together at one quality, but each will come out at a different size. Check the table and adjust the quality until the heaviest one is under the target.
Which is smaller at this target, JPEG or WebP?
It depends on the picture. Switch the format and read both sizes in the table, but first make sure the site you are uploading to accepts WebP.