Which image format belongs on your website?

Logos, icons, diagrams — SVG. It is drawn from shapes, so it is razor sharp at every size and usually a fraction of the size of a pixel image.

Photographs — AVIF first, WebP second. Both are supported by every current browser, and both make photos noticeably smaller than JPG at the same visible quality.

Screenshots and images with text — WebP in lossless mode, or PNG. Lossy compression smears text edges in a way people notice immediately.

Anything a visitor will download and reuse — JPG or PNG, because they open in everything, including software written decades ago.

WebP typically cuts a photograph by a quarter to a third against JPG at matching quality, and unlike JPG it supports transparency and animation. That makes it a single replacement for both JPG and PNG in most web work.

AVIF usually goes further still, especially on photographs with smooth gradients, and it handles a wider brightness range. The costs are encoding time — it is slower to produce — and slightly patchier support in software outside browsers.

The saving is not academic. Images are the majority of the bytes on most pages, and page weight is what makes a site feel slow on a phone on mobile data.

You do not have to choose one. The <picture> element lets a browser take the first format it understands, so you can offer AVIF, then WebP, then a JPG fallback, and every visitor gets the best file their browser can read.

Whatever you serve, give every image explicit width and height attributes so the page does not jump around as images load, and let images below the fold load lazily — but never the main image at the top, which should load as early as possible.

The Image Converter writes JPG, PNG, WebP, AVIF and more, in batches, without uploading anything — useful when the images are a client’s and you would rather they did not pass through a third party.

If you are unsure which format wins for a particular picture, the honest answer is that it depends on the picture. Encode it both ways and compare the file sizes; smooth photographs favour AVIF most, flat graphics often favour lossless WebP.