How to use the image compressor
- Drop one or more images on the drop area, or click it to choose files.
- Pick an output format: JPEG works everywhere, WebP is usually smaller at the same visual quality.
- Move the quality slider. Around 75–85% is a sensible starting point for photos.
- Check the size saving next to each file and look at the preview for visible artefacts.
- Download files one by one, or use “Download all”.
How it works
Each image is decoded by your browser, drawn onto an off-screen <canvas> at its original pixel size, and re-encoded with canvas.toBlob(type, quality). The quality value (0–1) is passed directly to the browser's JPEG or WebP encoder, which uses it to decide how coarsely to quantise the image's frequency components. Lower quality throws away more fine detail, so the file shrinks.
Re-encoding also drops metadata such as EXIF camera details and GPS location, which often saves a few kilobytes on its own. If the result would be larger than your original (common with already-optimised files), the tool tells you so instead of pretending it helped. For background on how these codecs differ, read our guide to JPEG vs WebP quality.
Worked example
A 4032 × 3024 smartphone photo saved as a 4.1 MB JPEG, re-encoded as JPEG at 80% quality, typically lands around 1–1.5 MB with no difference visible at normal viewing size. Saved as WebP at 80%, the same photo is often another 20–30% smaller. Exact numbers depend on the picture: a detailed landscape compresses less than a plain sky.
Limitations
- Compression is lossy: every re-encode discards some detail, so keep your originals.
- Pixel dimensions stay the same. To shrink much further, resize first with the Image Resizer.
- Animated GIF or WebP files are flattened to their first frame.
- Safari versions before 14 cannot encode WebP; the tool falls back and warns you.
- Very large images (over about 16.7 megapixels) may exceed browser canvas limits on some phones.
Frequently asked questions
What quality setting should I use?
For photos shown on screens, 75–85% is usually indistinguishable from the original. Go lower for thumbnails, higher for images that will be edited or printed.
Why did a file get bigger?
If the original was already heavily compressed, or was a PNG with few colours, re-encoding at a high quality can produce a larger file. Lower the quality or keep the original.
Are my photos uploaded to a server?
No. Decoding, compressing and preparing the download all happen in your browser tab. You can disconnect from the internet after the page loads and the tool still works.
Does compression remove location data?
Yes. Re-encoding through a canvas writes only pixel data, so EXIF metadata such as GPS coordinates and camera model is not copied into the new file.
Should I choose JPEG or WebP?
WebP is usually smaller at similar quality and supports transparency, and every current major browser displays it. Choose JPEG when the file must open in older software or be uploaded to a service that rejects WebP.