Iframe dimension sizing on Wix sites

Sites with explicitly sized iframe dimension sizing have a good CLS most often: 97%, against 96% of all Wix sites. Sites with unsized iframe dimensions have it least often, at 93%.

Explicitly sized is the most used: 65.3% of Wix sites.

React sets the iframe dimension sizing to explicitly sized on 65% of its sites, and 96% of React sites have a good CLS, against 96% of all sites.

FrameworkIframe dimension sizing on its sitesGood CLS

Wix sites with iframe dimension sizing 3,240 sitesExplicit width & height attributes 65%Unsized iframe (no width/height) 61%96%

React 3,240 sitesExplicit width & height attributes 65%Unsized iframe (no width/height) 61%96%

Explicit width & height attributes Unsized iframe (no width/height)

Does the framework explain the iframe dimension sizing difference?

On React, 97% of sites with explicitly sized iframe dimension sizing have a good CLS, against 93% of React sites with unsized. Within React, sites with explicitly sized and unsized have a good CLS about equally often.

Why visible iframes cannot infer an aspect ratio without attributes

Unlike images, an <iframe> has no intrinsic dimensions in its network header; without explicit width and height attributes or a sized container, the browser defaults the frame to 300x150 pixels until scripts resize it. Across iframe-using sites, 65.3% size their embeds explicitly (97% good CLS) and 61.2% include unsized iframes (93% good CLS, largely hidden utility sandboxes).