Guide
How to compress images without visible quality loss
Large images slow down websites, bounce off email size limits and fail on upload forms. Compression shrinks the file by removing information your eyes are unlikely to notice. Done well, a 5 MB phone photo can drop under 500 KB with no visible difference at normal viewing size.
Pick the right format first
- WEBP usually gives the smallest file at a given quality and is supported by all modern browsers. It's the best choice for websites.
- JPG is accepted absolutely everywhere, including older software, government portals and email. Use it when you're not sure WEBP will be accepted.
- PNG is lossless. It's ideal for screenshots, graphics and images with transparency, but it's the wrong choice for photos because the files stay large.
Choosing a quality setting
Quality is a trade-off between file size and detail. These starting points work for most photos:
- Websites and blogs: 72–82%.
- Email and messaging: 70–80%.
- Printing or archiving: 90–95%, or keep the original.
Resize before you compress
Pixel dimensions affect file size far more than the quality slider. A 4000-pixel-wide photo shown in a 1200-pixel-wide blog column is mostly wasted data. Resize it to the size it will actually be displayed at with the Image Resizer, then compress. The combination routinely cuts files by 90% or more.
Avoid compressing twice
JPG and WEBP compression is lossy: each time a compressed file is compressed again, more detail is lost and artefacts build up. Keep your original and always compress from it. If a result shows blocky patches in skies or halos around edges, raise the quality a few points and try again.
A side benefit: metadata is removed
Because compression re-draws the image in your browser, the output file doesn't carry over the original's EXIF metadata, such as GPS location and camera details. That's useful before sharing photos publicly. Nothing is uploaded at any point: the whole process runs on your device.