In this article we will explain why there is a general discrepancy in our viewability compared to Google.
Google uses the ad size to determine whether it’s a large or small banner. The definition of a large banner is that it’s 970x250 pixels (242.000 pixels)or larger. If it meets this size requirement, Google tracks a viewed impression when the banner has been in view for 30% of the screen for 1 second. Conversely, if the banner is smaller than 970x250 pixels, Google tracks a viewed impression when 50% of the banner is in view for 1 second.
At Adnami, we assess the size of the actual format to determine whether it’s a large or small banner. For desktop, we follow the same definition as Google: if the banner is equal to or larger than 970x250 pixels, it’s considered large; otherwise, it’s a small banner. However, since 970x250 is based on desktop devices, there isn’t an equivalent IAB standard for mobile yet.
Let us illustrate with a few examples:
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Topscroll on Desktop:
- When booking topscroll ads on desktop, the dimensions are set at 1x2 (i.e., 1 px wide and 2 px tall). If the topscroll ad is placed on a page and its actual size is 1920x1080 pixels:
- Google considers it a small banner due to the 1x2 dimensions, requiring 50% of the ad to be in view for 1 second to track a viewed impression.
- Adnami, on the other hand, classifies it as a large banner based on the actual size (1920x1080), requiring 30% of the ad to be in view for 1 second to track a viewed impression.
- When booking topscroll ads on desktop, the dimensions are set at 1x2 (i.e., 1 px wide and 2 px tall). If the topscroll ad is placed on a page and its actual size is 1920x1080 pixels:
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Midscroll on Mobile:
- For midscroll ads on mobile, the booking size is 320x480 pixels. If the midscroll ad is placed on a page and its actual size is 375x480 pixels:
- Google categorizes it as a small banner (since it’s smaller than 970x250 pixels), requiring 50% of the ad to be in view for 1 second to track a viewed impression.
- Adnami, however, defines it as a large banner (since it’s larger than 320x480 pixels for mobile), requiring 30% of the ad to be in view for 1 second to track a viewed impression.
- For midscroll ads on mobile, the booking size is 320x480 pixels. If the midscroll ad is placed on a page and its actual size is 375x480 pixels:
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Double Midscroll:
- For double midscroll it would be even more explicit since Google uses the ad unit size to determine if 30% or 50% has to be measured and then uses the full creative to actually measure. And since double midscroll is twice the size of a normal midscroll it would take even longer for Google to register viewability. Whereas we are still measuring after 30% of the creative.
It’s worth noting that when comparing impressions, raw data matters. We should focus on the number of viewed impressions for accurate comparisons. Google often tracks more impressions because they count them even before our third-party tag is fully loaded.
- For double midscroll it would be even more explicit since Google uses the ad unit size to determine if 30% or 50% has to be measured and then uses the full creative to actually measure. And since double midscroll is twice the size of a normal midscroll it would take even longer for Google to register viewability. Whereas we are still measuring after 30% of the creative.