How to use the image compressor
- Click "Choose an image" and pick a JPG, PNG or WebP file from your device.
- Drag the quality slider to set the trade-off between file size and picture quality — lower means a smaller file.
- Click "Compress Image" and wait a moment while your browser processes the picture.
- Compare the original and compressed sizes, then click "Download JPEG" to save the result.
How image compression works
JPEG compression works by discarding detail the human eye rarely notices, such as fine colour variations, while keeping edges and brightness intact. The quality setting controls how aggressively that detail is removed. At 0.9 the image looks almost identical to the original but is usually much smaller; at 0.4 it becomes smaller again but may show blocky artefacts in flat areas of colour.
Why compress images?
Large images slow down websites, clog email attachments and burn through mobile data. Search engines also reward faster pages, so smaller images can help your rankings. Compress before uploading a photo to a content management system, sending a picture by email, or reducing the storage used by a gallery.
A note on output format
This tool always outputs JPEG, because JPEG gives the best size reduction for photographs. If you need a different format, use the Image Converter instead. Transparent areas in PNG files are filled with a white background during compression.
Choosing a quality setting
| Quality | Best for |
|---|---|
| 0.9 | High-quality photos for the web |
| 0.7 | Everyday web and social media images |
| 0.5 | Email attachments and thumbnails |
| 0.3 | Small avatars and previews |
Lossy vs lossless compression
JPEG is a lossy format, which means some original detail is permanently discarded when you save. This is why you cannot recover the original file from a compressed JPEG — the discarded information is gone. Always keep a copy of the original if you think you might need it later. For images that must remain pixel-perfect, such as screenshots with small text, consider a lossless format like PNG and compress conservatively.
When not to compress
Some images should stay as large as possible. Print materials, high-resolution photographs destined for editing, and images with fine text can suffer visibly from aggressive compression. In those cases, set the quality high (0.9 or above) or skip compression entirely.