How to use it
Add one or many images and the tool re-encodes each one in your browser. For JPG and WebP the quality slider controls how much fine detail is discarded: 70 to 80 percent is usually the best balance, because the saving from 100 down to 80 is large while the visible change is small. For PNG, which is lossless, the slider instead reduces the number of colours (a palette), which works well for logos, screenshots and graphics but less well for photographs. If you need a specific size, switch to the target-size mode and enter the KB limit; the tool finds the highest quality that fits, and scales the picture down only if it must.
Each result shows the original and new size, the percentage and bytes saved and the final dimensions, and a before-and-after view lets you check quality before you download. If re-compressing would not make a file smaller (an already well-optimised JPG, for example), the original is returned unchanged rather than a bigger file, and the row says so. Converting between formats, limiting the longest side and choosing a background colour for transparent areas are all available, and several files can be saved together as a ZIP.
Everything runs locally, so private photos and documents are never uploaded, and re-encoding removes hidden metadata such as GPS position. Compression is always a trade-off, so keep your originals. To set exact pixel or centimetre sizes use the Image Resizer, to change the file type use the Image Converter, for application-form photos with strict limits use the Passport Photo Resizer, and to put pictures into a PDF use JPG to PDF Converter.
Supported formats and limits
| Input formats | JPG/JPEG, PNG and WebP; GIF, BMP and AVIF too if your browser can open them. HEIC is not supported by most browsers. |
|---|---|
| Output formats | Same as the original, or JPG, WebP or PNG. WebP output needs a browser that can encode it (for example Chrome or Edge); the tool tells you if yours cannot. |
| Batch size | Up to 50 images at once, each up to 60 MB and 120 megapixels. Download one by one or all as a ZIP. |
| Modes | By quality (10–100%) or to a target size in KB, with an optional limit on the longest side in pixels. |
| What is lost | JPG and WebP are lossy: fine detail is discarded. PNG is reduced by lowering its colour count. EXIF metadata (GPS, camera) is removed. |
| Privacy | Processed locally with the browser's Canvas. No upload, no account, nothing stored. |
Practical examples
A phone photo for an email
- Situation
- A 4 MB photo straight from a phone camera, compressed by quality at the default 75%.
- What to expect
- Phone photos often shrink by half or more with no visible difference at normal viewing size, though the saving depends on the picture. The result panel shows the exact bytes saved and a before/after preview.
A form that wants a file under 100 KB
- Situation
- Choose “To a target file size”, enter 100 and drop the picture.
- What to expect
- The tool searches for the highest quality that fits under 100 KB. If quality alone cannot get there, it also scales the picture down and tells you the new dimensions.
A PNG logo with flat colours
- Situation
- A transparent PNG compressed at 75%.
- What to expect
- The colour palette is reduced (here to 128 colours), which can shrink flat graphics a lot while keeping transparency. Photos saved as PNG shrink less, because JPG or WebP suits them better.
The numbers behind it
saving (%) = (original size − new size) ÷ original size × 100file size ≈ pixels × bits per pixel ÷ 8 (so fewer pixels or lower quality means a smaller file)
- Quality 100% = least compression; lower values discard more detail
- 1 KB = 1024 bytes, as your operating system shows it
Compression trades some invisible detail for a smaller file; the tool shows exactly how many bytes it saved.
Honest limits
- JPG and WebP compression is lossy; keep your originals.
- A well-optimised file may not shrink further, and then the original is returned unchanged.
- Very large images (over 120 megapixels) and files over 60 MB are skipped to protect your device's memory.
- Animated GIFs and WebPs keep only their first frame.