Resizing a JPG
A JPG stores a picture as blocks of colour detail. Resizing it means that the browser decodes it, scales the pixels and writes a new JPG. Making a JPG smaller keeps it sharp, and it also makes the file much smaller: half the width and height leaves a quarter of the pixels.
Quality after resizing
Every JPG save is lossy, so resizing a JPG costs a little detail even at high quality. This page saves at quality 90, which is hard to tell from the original at normal size. Lower it for smaller files. Higher than 95 adds a lot of size and little that you can see.
| Quality | Result |
|---|---|
| 92 to 95 | Archive and print, big files |
| 85 to 90 | Clean at any normal size. A good default. |
| 75 to 80 | Websites and email |
| Below 60 | Blocks appear around edges |
Tips for resizing JPGs
- Resize from the original. Do not enlarge a JPG that was already shrunk.
- Do it once. Do all your changes (size and format) in one step to avoid repeated losses.
- Transparency. JPG has none. Transparent parts of a PNG become the background colour you choose.
- EXIF data such as GPS is removed. The orientation is applied first.
You can also resize PNG, WebP and HEIC files, or shrink a JPG to a limit: 100 KB, 200 KB, 500 KB. For quality-first shrinking, use the JPG compressor.