Mobile: Illegible Font Size

Pages with small font sizes that can make it difficult to read for users on mobile devices.

Lighthouse will flag pages that have font sizes smaller than 12px, which make up more than 40% of the page text.

How to Analyse in the SEO Spider

To populate this filter the PageSpeed Insights API must be connected via ‘Config > API Access > PSI’.

View URLs with this issue in the ‘Mobile’ tab and ‘Illegible Font Size’ filter.

Use the lower ‘Lighthouse Details’ tab to click on the issue on the left-hand side, and see details of the Illegible Font Size on the right-hand side.

Bulk export the pages and details of the Illegible Font Size via ‘Reports > Mobile > Illegible Font Size’.

What Triggers This Issue

This issue is triggered by Lighthouse when pages have a font size smaller than 12 px on more than 40% of the text.

How To Fix

Review font sizes in the CSS and consider increasing them to at least 12 px on at least 60% of the text on the page for improved mobile usability.