Image compressor

This is why your website is slow

It is almost always the pictures. A phone camera writes four or five megabytes an image. Eight of those on one page is forty megabytes, and no amount of hosting fixes it — on mobile data that page takes half a minute whatever server it sits on.

A photograph on a website rarely needs to be wider than about 1600 pixels, and at that size in WebP it is usually under 200KB. The same page becomes two megabytes instead of forty, and it loads before somebody gives up.

Which settings to use

WebP at 80% quality and 1600px wide is the setting to start from, and it is right for most photographs on most sites. If your images sit inside a column rather than spanning the page, 1200px is plenty and the file is smaller again.

Use PNG only for logos, diagrams and screenshots of text — anything with hard edges and flat colour. A photograph saved as PNG is often five times larger than the same picture as WebP, with no visible difference.

When judging quality, look at skies, water and skin. Those are where compression shows first; brickwork and foliage hide it for much longer.

Nothing is uploaded

Every picture is read, resized and re-encoded by your own browser. Nothing is sent to us, which means there is no size limit we impose, no queue to wait in, and no copy of your photographs sitting on somebody else’s server afterwards.

That also means the work is done by your computer. Twenty large photographs will make a laptop warm, and an old phone will take a moment over each one. That is the trade for a tool with no upload and no account.

After you compress them

Replace the originals on your site rather than adding the new ones alongside. A compressed copy uploaded next to a four-megabyte original does nothing at all if the page still points at the original.

Keep your originals somewhere safe. Compression is one-way, and a photograph you may want to print later should be kept at full size off the website — the version on the page is for the page.