What Is Ad Fill Rate in Advertising?

Ad Fill Rate is a key performance metric in digital advertising that measures the percentage of ad requests that are successfully filled with ads. It is an important indicator of how efficiently a publisher’s ad inventory is being utilized, and it can impact revenue potential.

A higher ad fill rate means that more of the available ad space is being monetized, which is generally a positive sign for both advertisers and publishers.

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 percentage, which represents how efficiently your ad inventory is being filled. A higher percentage typically indicates better ad inventory management, while a lower percentage suggests missed opportunities.

Try our Ad Fill Rate calculator to better understand this metric.

Ad Fill Rate Formula

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.

Ad Fill Rate vs. CPM (Cost Per Thousand Impressions)

While ad fill rate is an important metric for understanding how much ad inventory is being utilized, it is different from CPM (Cost Per Thousand Impressions). CPM is a measure of how much revenue is earned per 1,000 ad impressions, while ad fill rate focuses solely on how many of your available ad requests are actually filled.

Improving Your Ad Fill Rate

If you're experiencing low fill rates, here are a few strategies you can use to improve:

1. Use Multiple Demand Sources: Work with several ad exchanges, networks, or DSPs to increase demand for your inventory and improve fill rates.
2. Optimize Ad Targeting: Ensure your ads are being served to the most relevant audiences, as this can improve both fill rates and engagement.
3. Increase the Diversity of Ad Formats: Different ad formats (like display ads, video ads, and native ads) might have different fill rates depending on the platform and audience. Experiment with different formats to see which works best for your audience.
4. Monitor and Adjust Inventory: Continuously monitor ad fill rates across different sections of your website or app. If certain ad units consistently have low fill rates, it may be time to adjust your pricing or targeting strategies.

The Ad Fill Rate is a vital metric for digital advertisers and publishers to understand how well their ad inventory is being utilized. By calculating the fill rate and optimizing your ad strategies, you can ensure higher efficiency, improved revenue potential, and better ad performance.