How to use the JPEG Compressor
- Drag in the JPG, JPEG or JFIF pictures, or a folder of frames exported from your editor.
- Leave the quality slider at 75, or slide it down toward 60 when the files only need to look good on a phone screen.
- If a site demands a hard limit, open More settings and type a size in KB; you can also set a smaller width there.
- Press Compress and compare the old and new size listed under each picture before downloading.
Where the bytes go
A phone usually writes its photos at a quality in the low to high nineties, far above what anyone notices on a screen. Bringing that down to 75 tends to strip well over half the file while the picture still looks the same in a gallery or a message thread.
MozJPEG is an encoder from Mozilla that produces ordinary JPGs, just packed more tightly: progressive scans, tuned quantisation and optimised Huffman coding. Anything that opens a JPG opens these, from old photo viewers to video editing timelines.
Using a target size instead of quality
With a KB target set, the tool tries different qualities and keeps the highest one whose result fits. When a large frame cannot fit even at the lowest quality, it scales the picture down a step at a time and tries again, so you still end up with a file under the limit.
The target counts a kilobyte as 1024 bytes. A picture that is already below the target and is not being resized is handed back untouched rather than compressed for nothing.
Questions
What if the compressed file is not smaller?
When the format stays JPG and no resize is set, a result that is the same size or larger is discarded and you get your original back.
Is location data removed?
Yes. Re-encoded pictures are written without EXIF, so GPS position and camera details are gone. Before that, any orientation flag is baked into the pixels, which keeps portrait shots upright.
Should I compress the same JPG twice?
It is better not to. A second pass saves little and adds more loss; start from the best copy you have.