Compress JPEG Online — Quality Slider, Live Size
Shrink JPEG photos with a live quality slider. Runs in your browser — files never leave your device. No upload — runs 100% in your browser
or click to browse
How to use this tool
- Drop an image onto the box above.
- Move the slider — the output size updates live.
- Click Download when the size looks right.
How JPEG compression works
JPEG throws away the visual information your eye is least sensitive to — fine color detail — using a mathematical transform (the discrete cosine transform) on 8×8 pixel blocks. The quality slider controls how aggressively it rounds those numbers: 90+ is visually indistinguishable from the original for photos, 70–80 is the usual sweet spot for web use, and below 50 you start seeing blocky artifacts around edges and text. Because the savings come from smarter encoding rather than fewer pixels, the image keeps its full dimensions at every setting.
Frequently Asked Questions
Are my files uploaded to a server?
No. Everything on this page runs inside your browser using JavaScript and WebAssembly. Your file never leaves your device — you can even disconnect from the internet after the page loads and the tool still works.
What quality should I pick?
80 is a good default for web and email. Use 90+ if the photo will be printed, and 60-70 when you need the smallest file that still looks fine on screen.
Does it keep transparency?
Yes. Both tools preserve the alpha channel of PNG/WebP sources. Only the JPEG output of other tools flattens transparency to white.
Is there a size limit?
No hard limit — decoding happens in your browser, so the practical limit is your device memory.