What this tool does
Re-encodes a JPG, PNG or WebP image in the browser at a selected quality and output format, then reports the resulting size.
How to use it
- Choose a JPG, PNG or WebP image within the limits shown above.
- Select the output format and JPG/WebP quality; PNG does not use the quality setting.
- Check the encoded preview, dimensions and size change, then download.
Method
Canvas re-encodes the decoded image at its natural pixel dimensions. Size change compares output bytes with original bytes: a larger file is shown as an increase. JPG and WebP use the chosen quality; PNG ignores it. If the browser cannot encode the selected format, choose PNG.
Worked example
If a 100,000-byte image becomes 140,000 bytes, the result is 40% larger. Width and height stay unchanged. A lower JPG/WebP quality can reduce size, but no compression ratio is guaranteed.
Common uses
- Reducing web image transfer size
- Making email attachments smaller
- Comparing JPG and WebP output
Limitations
JPG fills transparent areas with white. Animated images become a still image. Metadata and color profiles may change; complete metadata removal is not guaranteed. Re-encoding can reduce quality or increase file size. Check the preview and downloaded file, and retain the original.
FAQ
Why did PNG not get smaller?
PNG ignores the quality setting. Re-encoding may produce a larger file; use JPG or WebP when their tradeoffs are acceptable.
Does compression change width and height?
No. This tool keeps the decoded natural dimensions; use the resizer to change pixels.