About this tool
JPG Compressor, Reduce JPEG File Size Free Online
Compress JPEG and JPG images to a fraction of their original size without visible quality loss. OmegaPix uses the mozjpeg encoder, the same technology behind many professional image pipelines, to produce smaller files with better sharpness than default JPEG encoding. Because everything runs in your browser, your photos are never sent to a server and compression finishes in seconds regardless of your internet speed.
Why use OmegaPix
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mozjpeg, 5–15 % better than standard JPEG : mozjpeg applies advanced Huffman table optimisation and trellis quantisation that standard libjpeg cannot match. Smaller files at the same quality setting.
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No server, no exposure : Your personal photos and confidential images are processed entirely inside your browser. They never travel over the network.
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Batch JPEG compression with ZIP : Compress hundreds of JPEG files at once and download all results as a single ZIP archive. No clicking through repeated uploads.
How it works
Upload your JPG files
Drag one or many JPEG images into the drop zone. All common JPEG extensions (.jpg, .jpeg, .jfif) are accepted.
Set your quality target
Auto quality picks the smallest file with no visible degradation. For print or archival use, set Manual quality to 90–95 to keep maximum detail.
Download smaller JPEGs
See the new file size and savings for each image. Download the compressed JPEG or grab all outputs as a ZIP.
Frequently asked questions
What is the difference between JPG and JPEG?
JPG and JPEG refer to the exact same image format. The .jpg extension originated on Windows, which originally required three-character file extensions. Both extensions produce identical files and are interchangeable.
How does OmegaPix compress JPEG files?
OmegaPix uses the mozjpeg encoder compiled to WebAssembly. mozjpeg applies advanced Huffman table optimisation and trellis quantisation, typically producing files 5–15 % smaller than standard libjpeg at the same visual quality level.
Will compressing a JPEG further degrade quality each time?
Yes, JPEG uses lossy encoding, so re-compressing an already-compressed JPEG introduces additional quality loss. Always keep your original files and compress from the original, not from a previously compressed copy.
Can I convert JPG to WebP for even better compression?
Yes. Switch the output format to WebP before compressing. WebP typically achieves 25–35 % better compression than JPEG at equivalent visual quality and is supported by all modern browsers.
Is there a file size limit for JPEG compression?
There is no hard file size cap. The practical limit is your device's available memory. OmegaPix will warn you before accepting files that would exhaust your RAM.
Does OmegaPix preserve EXIF metadata when compressing JPEG?
OmegaPix strips EXIF metadata during compression to produce the smallest possible file. If you need EXIF data preserved, for example, GPS coordinates or camera settings, keep a backup of the original before compressing.
What JPEG quality setting should I use for web images?
Auto quality is recommended for most web images. If you prefer manual control, quality 75–85 covers most web use cases. Quality 60–70 gives aggressive savings that are still acceptable for thumbnails and preview images. Anything below 60 typically shows visible artifacts.
Can I compress JPEG images on my iPhone or Android?
Yes. OmegaPix runs in mobile browsers including Safari on iOS 15.2+ and Chrome on Android. Tap the browse button to select photos from your camera roll, or transfer files via AirDrop or USB and compress in your phone's browser.
Does JPEG support transparency?
No. JPEG does not support alpha transparency. If you need transparency, use PNG for lossless, WebP for lossy compression with transparency, or AVIF for maximum compression with transparency support.
How does JPEG compare to WebP and AVIF in 2026?
JPEG remains widely compatible but is technically outdated. WebP achieves 25–35 % smaller files than JPEG at the same visual quality, with full browser support. AVIF achieves 40–50 % smaller files than JPEG but encodes more slowly. For new web images, WebP is the pragmatic choice; for maximum compression where encoding time is acceptable, AVIF wins.
When to use this tool
Use JPEG for photographs going online
JPEG is still the right choice for photographic content where the platform may not support WebP, email clients, certain CMS platforms, and legacy social apps.
Avoid JPEG for graphics with transparency
JPEG does not support alpha transparency. Use PNG or WebP instead for logos, illustrations, or any image that needs a transparent background.
Never re-compress an already-compressed JPEG
Each JPEG compression pass compounds quality loss. Always compress from your original, uncompressed file. Keep originals in a separate folder.
When not to use this tool
JPEGs with text or sharp edges
JPEG compresses photos beautifully but adds halos around text and line art. For screenshots and graphics, use PNG or WebP-lossless instead.
Final-edit master files
JPEG re-compression is cumulative. Every save loses a little. Keep an uncompressed master (PNG or original RAW) and compress only the export.
Print-ready files
Print needs 300 DPI uncompressed data. Web-quality JPEGs at q80 show visible blocking when scaled to print sizes.
Technical details
How JPEG compression actually works
JPEG splits the image into 8×8 pixel blocks, converts each to frequency space via DCT, then quantises the high-frequency components. The parts your eye is less sensitive to. The quality setting controls the quantisation table aggressiveness. Quality 100 keeps everything; quality 50 throws away half of the high-frequency detail; quality 20 destroys legibility.
Quality settings that matter
For web photographs, quality 85 is visually lossless, almost no viewer can tell it apart from quality 100 at normal screen distance, but the file is ~55% smaller. Quality 80 is the sweet spot for email and sharing: still indistinguishable to a casual viewer, ~65% smaller. Below quality 70, compression artefacts start showing on smooth gradients (skies, skin). Below quality 50, blocking becomes obvious.
mozjpeg vs browser-native encoder
Browsers ship a built-in JPEG encoder that gets the job done but uses default quantisation tables. OmegaPix uses mozjpeg, Mozilla's research-grade encoder, which uses smarter trellis quantisation and progressive scan optimisation. The result: typically 5-15% smaller files at identical visual quality compared to canvas.toBlob().
Real numbers
A 4032×3024 iPhone JPEG at original quality (~95) is 4.2 MB. Recompressed to q85 via mozjpeg: 1.8 MB (-57%). To q80: 1.1 MB (-74%). To q70: 720 KB (-83%), visible artefacts on close inspection. To q60: 480 KB (-89%), visibly degraded.
Your files stay on your device
JPEG compression runs entirely in your browser. The mozjpeg encoder compiles to WebAssembly and processes each file locally, your photo bytes are never transmitted. Open DevTools → Network during a Compress action: you'll see zero outgoing requests carrying image data.