Compress JPEG images
This recompresses JPEGs as JPEGs, using MozJPEG rather than a conventional encoder. Trellis quantisation, optimised Huffman tables and progressive encoding together produce files around 20-35% smaller than a typical camera or export JPEG at the same visual quality — and the output is still an ordinary JPEG that opens anywhere.
What to know
- Recompressing a JPEG is generational loss. Quality 80 and above keeps this invisible; repeated passes at low quality will not.
- Progressive encoding is used, which is both smaller and renders top-to-bottom on slow connections.
- EXIF, ICC colour profiles and XMP are preserved, so camera data and copyright survive.
- If you can use a modern format, converting to WebP or AVIF saves considerably more than recompressing.
Frequently asked questions
- How can a JPEG get smaller without changing format?
- Most JPEGs are written by encoders optimised for speed, not size. MozJPEG spends far more effort searching for efficient encodings — trellis quantisation in particular tunes the coefficients per block. Combined with optimised Huffman tables and progressive scan ordering, that finds 20-35% with no change in visual quality.
- Does recompressing a JPEG lose quality?
- Yes, slightly — decoding and re-encoding a lossy format always does. At quality 80 or above it is not visible at 100% zoom. Avoid repeatedly compressing the same file, as the loss accumulates.
- Will compressing keep my EXIF data?
- Yes. EXIF, ICC colour profiles and XMP are extracted and written back into the compressed file, so camera settings, copyright and GPS data survive. You can turn this off to strip metadata before publishing.