Could your image markup cause layout shifts?
It identifies image patterns associated with shifting layout, rather than measuring a browser score.
What Check Engine measures
A page needs at least 3 images with URLs, excluding detected tracking images. More than a 0.6 share must lack recorded dimensions. At least one image missing dimensions must be outside the shared template. An image counts as shared only with at least 5 successful pages and presence on at least a 0.6 share. These limits keep repeated logos alone from triggering the same risk on every page. For example, a missing-dimensions share of exactly 0.6 does not exceed the risk threshold.
The check reads image markup from successful pages. It does not measure movement in a browser. Use a browser measurement when you need an actual layout-shift score.
How to read the result
The finding is medium severity. It reports a markup risk, not a measured Core Web Vitals result or a prediction of the exact amount a page moves during loading.
Why it matters
Dimensions can reserve space before an image arrives. The check looks for missing space in image markup and accounts for shared template images. Use a browser to see the movement a visitor actually experiences.
How to fix it
Set correct image dimensions or reserve the intended aspect ratio in the relevant component. Review content images as well as repeated logos. Test the page visually while images load and use suitable browser measurements for an actual layout-shift result. Keep the source fix tied to the missing space rather than claiming a numerical score improvement from this check alone.
What we found in field audits
Problems in Speed & Core Web Vitals were found on 13 of the 14 sites we audited. These are area totals. Read the field-audit method.
Method note
backend/seo_engine/checks/performance.py, cls_risk, revision 0bb8e8d3.
Common questions
How many images are needed for the markup-based layout-shift risk check?
The minimum is 3 images with URLs after tracking-image exclusions. Missing dimensions must also pass the share and template guards.
Does a missing-dimensions share of 0.6 trigger layout-shift risk?
No. The share must be greater than 0.6. A qualifying image outside the shared template is also required.
Does the image layout-shift check measure a browser CLS score?
No. It reports a medium severity markup risk. Actual movement and the browser score need separate measurement.