How to compress images for your website without uploading them

Images are usually the heaviest thing on a web page. A photo straight from a phone camera can be 4MB or more, and a page with five of them will feel slow on a mobile connection however good the rest of the site is. Search engines notice slow pages too.

The fix is simple: make each image only as large as it is shown, and save it at a sensible quality. Our free image compressor does both, and it does it without uploading anything.

Compress your images in four steps

1. Open the tool. Go to the Tools page. The Image Compressor is the second card.
2. Add your images. Drag JPG, PNG or WebP files onto the box, or click it to pick them. You can add several at once.
3. Pick a quality and a maximum width. The defaults (75% and original size) are a good start; the next section explains when to change them.
4. Press Compress images. Each file appears with its old size, its new size and how much was saved. Click Download next to each one.

Which settings to use

Quality. Somewhere between 70% and 80% is the sweet spot for photos. Most people cannot tell the difference from the original on a screen, and the file is often a fraction of the size. Go higher only for images where fine detail matters, such as product close-ups. Go lower for small thumbnails.

Maximum width. This makes a bigger difference than quality. There is no point sending a 4000-pixel photo to a space that is 800 pixels wide. As a rough guide:

• 1920px for full-width banners and hero images.
• 1280px for images inside an article or a product page.
• 800px for thumbnails, cards and gallery previews.
• Original size only if you will resize the image somewhere else later.

The height is scaled to match, so nothing is stretched or cropped.

The one kind of image to leave alone

The compressor saves PNG files as JPG, because JPG is far smaller for photos. JPG has no transparency, though, so a logo or an icon with a see-through background will lose it. Keep logos, icons and screenshots of text as PNG (or use an SVG for logos), and use the compressor for photographs.

WebP images stay WebP, and JPG images stay JPG.

"Already optimized"

Sometimes a file comes back marked already optimized. That means compressing it would not have made it any smaller, so the tool hands back your original instead of a worse copy of the same size. It will never give you a file larger than the one you started with.

Nothing leaves your computer

The whole job happens inside your browser tab. The image is drawn onto a canvas, resized, and saved again, all on your own device. Nothing is uploaded, there is no server involved, and once the page has loaded you could switch off your internet connection and it would still work. That makes it safe for photos you would not want to send to a stranger's server, such as pictures of documents or of your family.

Why it is free

We build websites and software, and slow, heavy images are one of the most common problems we fix on other people's sites. A free tool that solves it in a minute seemed more useful than another article about it. There is more on how we think about free tools in why our free tools don't ask for your email, and if your site needs more than lighter images, get in touch.