Convert image

Convert images, keep the ratio.

Turn JPG, PNG and WebP files into the format you need, optionally capped to a max width or height. Images are never enlarged, and the aspect ratio is always preserved.

Drop images to convert

Up to 10 files, 20.00 MB each. JPG, PNG, WebP, GIF, BMP.

Choose a file

How it works

  1. 01Add up to 10 images (20.00 MB each).
  2. 02Choose the output format and optional size cap.
  3. 03Every file is converted in your browser and listed with its own download.

Supported formats

Input: JPG, PNG, WebP, GIF and BMP. AVIF works only if your browser decodes it. HEIC/HEIF is not supported — FormatOnce bundles no HEIC decoder, so export those photos as JPG first.

Output: JPG, PNG, WebP (whatever your browser can encode). Output is capped at 40 megapixels.

Questions & limits

Can I convert HEIC photos from my iPhone?
No. FormatOnce does not bundle a HEIC decoder, and most browsers cannot decode HEIC either. Export as JPG on your device, then convert here.
Does converting enlarge small images?
Never. Max width and max height only shrink an image; smaller images keep their size.
What about transparency?
PNG and WebP keep transparency. JPG cannot, so transparent pixels are flattened onto white.
Why is one file greyed out as unavailable?
That output format is not supported by your browser's canvas encoder. Pick another format.