How to use
- Add images.
- Choose a mode: width/height, percentage, longest side or fit within a box.
- Resize, then download or send the results to the compressor.
Worked example
Width 200 px with Keep aspect ratio on turns a 400×200 image into 200×100. Longest side 1600 px turns a 4000×3000 photo into 1600×1200 and a 3000×4000 photo into 1200×1600.
Supported formats and limits
| Input | JPEG, PNG, WebP, AVIF, BMP, TIFF, HEIC, GIF (first frame) |
|---|---|
| Output | Same format as input, or JPEG/PNG/WebP/AVIF |
| Limits | Up to 50 megapixels per image; 200 images per batch. |
| Engine | Multi-step high-quality canvas resampling in a Web Worker |
Limitations
- Enlarging an image cannot add detail, and images are not enlarged unless Allow enlarging is on.
- Animated GIFs are resized from their first frame only.
- JPEG output has no transparency; transparent areas become white.
Questions
Will resizing stretch the image or crop it?
Neither, unless you choose it. Width/height with Keep aspect ratio on, Percentage, Longest side and Fit in box all keep the proportions and use the whole image. Turning Keep aspect ratio off with both sides filled stretches to exactly that size. Exact (crop) fills the size and cuts off the overflow, keeping the part you pick (centre, a side or a corner).
What if an image is already smaller than the size I enter?
It keeps its size and the result is marked as not enlarged. Turn on Allow enlarging to scale it up; that cannot add detail.
Which format are the results saved in?
The same format as each original by default (HEIC becomes JPEG; ICO and SVG become PNG), or JPEG, PNG, WebP or AVIF for all files. A quality slider applies to JPEG, WebP and AVIF.
Guides
- Choosing an image format: JPEG, PNG, WebP or AVIF
- Favicons in 2026: which sizes and files you actually need
- Open Graph tags and social preview images: sizes and fixes
Privacy
Runs on your device. Files and text are processed in this browser tab and are not uploaded.
See the privacy policy for how toolsdocks handles data.