Missing Image Size Attributes

What This Means

One or more <img> elements are missing width and height attributes. Without these attributes, the browser cannot reserve the correct amount of space for the image before it loads.

Why It Matters for SEO

When a browser encounters an <img> without width and height, it initially renders the element at zero size. When the image file loads and its dimensions become known, the browser resizes the element — pushing all subsequent content down. This is Cumulative Layout Shift (CLS), a Core Web Vitals metric.

Even small CLS values accumulate across multiple elements — a page with several images all loading without reserved space will typically have a high CLS score. Google uses CLS as a page experience ranking signal.

What the Platform Checks

The platform checks each <img> element for the presence of both width and height attributes. Fires when either is missing.

How to Fix It

Add width and height attributes to all <img> elements:

<img src="product.jpg" alt="Product description" width="800" height="600">

• Set the attributes to the image's intrinsic dimensions — not the display dimensions. CSS can still scale the image visually.
• The browser uses the ratio of width:height to reserve the correct space before the image loads.
• For responsive images: use aspect-ratio CSS as an alternative to explicit width/height attributes in some frameworks.
• In CMSs: update the image insertion template to always include width and height attributes from the media library metadata.