Every edit saves the image again
When a tool changes an image — crop, resize, filter, watermark — your browser draws the result and saves it as a new file. Nothing is copied over unchanged from the original. That has three effects worth knowing about.
1. JPEG and WebP lose a little each time
Both formats save space by throwing away detail you are unlikely to notice. The quality setting controls how much: around 85 and above the difference is not visible at normal size; below about 60 it starts to show as blocks in skies and skin. The loss adds up if the same image goes through several tools one after another, so keep your original and work from it each time.
2. The file can come out larger
- Saving a photo as PNG keeps every pixel exactly, and the file can be four or five times larger than the JPEG you started with. PNG is the right choice for logos, screenshots and anything with transparency, not for photos.
- Saving an already well-compressed JPEG at high quality can produce a bigger file than the original. The Image Compressor says so when that happens and suggests keeping the original.
Resizing makes by far the biggest difference to file size: half the width and height is a quarter of the pixels. The Image Resizer is the place to start for a photo that is too big to upload.
3. Camera data is not carried over
The location, date, camera model and other details stored inside a photo are left behind when the browser saves the new file. The image is turned the right way up first, so a sideways phone photo comes out upright. If you only want to remove that data and change nothing else, use the Image Metadata Remover.
Which format for what
- Photos for the web or messages: JPEG or WebP, quality 80 to 90.
- Logos, icons, screenshots and text: PNG, or WebP.
- Anything with a transparent background: PNG or WebP — never JPEG. See A transparent background turned white or black.