Best Image Dimensions for Websites

Measure the rendered width

Start with the largest CSS size the image reaches. A content image displayed at 800 pixels wide does not need a 5000-pixel source. High-density screens may benefit from an image around twice the rendered width.

Create variants for responsive layouts

A full-width desktop hero and a small mobile card have different needs. Responsive image sources allow the browser to choose an appropriate file instead of downloading one oversized asset everywhere.

Dimensions are only one layer

After resizing, choose WebP, JPG, or PNG based on the content and apply suitable compression. Test the result in the actual page to confirm both sharpness and crop behavior.