How image compression works
Photos from phones and cameras store far more detail than most screens can show. Compression drops the detail your eye is least likely to miss and stores the rest more efficiently. JPG and WebP let you decide how much to drop with a quality setting.
PNG works differently. It is lossless, so it keeps every pixel and has no quality setting. That makes PNG a good fit for screenshots, logos and graphics with flat colors, and a poor fit for photos.
This tool decodes each image in your browser, draws it on a canvas, scales it down if you set a max width, and encodes it again. If the new file is not smaller than the original, you get the original back, marked as already optimized.
Re-encoding also removes metadata such as EXIF data, camera details and GPS location. That is useful for privacy when you post photos online. If you need that information, keep your original files.
How to compress an image
- 1Drop your JPG, PNG or WebP files on the upload area, or tap it to pick files from your device.
- 2Choose a quality, an output format and, if the images are very large, a max width. The results update right away.
- 3Check the new sizes, then download single images or all of them at once as a ZIP file.
Which format should I use?
- WebP for images on websites. It usually gives the smallest files and supports transparency.
- JPG for photos you email or share, because every device and app can open it. JPG has no transparency, so transparent areas turn white.
- PNG for screenshots, logos and icons with sharp edges, or when you need lossless quality.
Frequently asked questions
Are my images uploaded to a server?
No. Your browser reads, resizes and re-encodes every image on your own device. The files never leave your computer or phone.
Which quality setting should I use?
Start with 80. It keeps photos looking sharp while making the file much smaller. Try 60 or 70 for thumbnails, and go up to 90 if you see blocky patches in skies or smooth gradients.
Should I convert my images to WebP?
For websites, usually yes. WebP files are typically smaller than JPG files at a similar quality, and all current major browsers display them. Keep JPG when you send images to people or apps that may not open WebP.
Is there a limit on file size or the number of images?
There is no fixed limit. Images are compressed one after another, so a large batch takes a little longer. Very large photos can fail on phones with little memory. If that happens, pick a max width and try again.