This audit ensures that ads take up no more than 30% of the page vertically. An ad density greater than 30% has been found to negatively impact user experience1.
Depending on the situation, slots should either be spaced farther apart or have a reduced size.
On mobile devices, we assume a single column layout and so all ads on the page are included in the ad density calculation. On desktop, we divide the page into multiple vertical slices to account for multi-column layouts. The audit measures ad density in each slice individually to ensure no individual slice exceeds the maximum recommended threshold.
To account for lazy loading, we measure content length up to 1 viewport past the last ad. To measure ad density over the entire content, disable lazy loading.
Coalition for Better Ads. "Determining a Better Ads Standard Based on User Experience Data". 2017. ↩