What is ad fill rate?

Ad fill rate is a key performance metric in digital advertising that measures the percentage of ad requests that are successfully filled with ads.

How to Calculate Ad Fill Rate?

Ad fill rate is calculated by dividing the number of total ad impressions (ads served) by the number of total ad requests. The result is then multiplied by 100 to get the fill percentage. This percentage represents how efficiently ad inventory is being utilized. Higher fill rates typically indicate better ad inventory management and higher revenue potential.

Ad Fill Rate formula

Use this formula to calculate Ad Fill Rate:

Ad Fill Rate = (Total ad impressions / Total ad requests) * 100

Ad Fill Rate calculation example

Suppose a publisher’s website generates 200,000 ad requests in a month, and 150,000 of these requests are successfully filled with ads. The ad fill rate would be calculated as follows:

Ad Fill Rate = (150,000 ad impressions / 200,000 ad requests) * 100 = 75%

In this example, the ad fill rate is 75%, meaning 75% of the ad requests resulted in an ad being served.

In addition to looking at which ad network can deliver the highest eCPM, publishers also look at which network can deliver the highest fill rates - since these are the networks that can fill a high percentage of requests.