Compress JPEG Online
Reduce JPEG file size using MozJPEG — the best JPEG encoder. 100% private, no upload.
How JPEG Compression Works
img.awajis uses MozJPEG, Mozilla's optimized JPEG encoder compiled to WebAssembly. MozJPEG produces files 5-10% smaller than standard JPEG encoders at the same visual quality. All processing runs directly in your browser — your images are never uploaded to any server.
When to Use JPEG
JPEG is ideal for photographs and images with smooth color gradients. It uses lossy compression, meaning some data is discarded to achieve smaller sizes. At quality 80, most images look indistinguishable from the original while being 60-80% smaller.
Quality Settings Guide
- 95: Near-lossless. Minimal size reduction but preserves fine details.
- 80: Recommended. Excellent quality with significant size savings.
- 60: Good for web thumbnails. Visible artifacts on close inspection.
Want even smaller files? Try converting to WebP for 25-35% more savings, or batch compress multiple images at once.
Frequently asked questions
How much smaller will my JPEG get?
At quality 80 most photos shrink by 60–80% with no visible loss. MozJPEG typically produces files 5–10% smaller than standard encoders at the same quality.
Does compressing a JPEG lose quality?
JPEG is lossy, so some data is discarded, but at quality 75–85 the difference is invisible to the eye. Lower settings save more space at the cost of visible artefacts.
Are my images uploaded anywhere?
No. Compression runs entirely in your browser with WebAssembly; your files never leave your device.
Can I compress many JPEGs at once?
Yes — drop several images, or use the Batch Compress tool to process up to 20 and download them as a ZIP.
What quality setting should I use?
For the web, quality 75–85 is the sweet spot — small files with no visible loss. Use 90+ for print or archiving, and 60–70 only for thumbnails where size matters more than fine detail.
Why is my JPEG still large after compressing?
Very high-resolution photos stay large even at a good quality. Resize the image to the dimensions you actually need first, then compress — the two steps together give the biggest reduction.
Does compressing the same JPEG twice help?
Not usefully. Re-compressing an already-compressed JPEG discards more detail for little extra saving, so always compress from the highest-quality original you have.
Does compression remove my photo’s metadata?
Re-encoding drops most EXIF metadata as a side effect. To be certain GPS and camera data are gone before sharing, run the Strip EXIF tool.