What is Ad Fill Rate Definition? Tips To Increase Fill Rate

Ad fill rate is a critical metric for publishers aiming to maximize revenue from their website or app. It measures the percentage of ad requests that are successfully filled with ads. For instance, if you have an ad fill rate of 80%, it means that 80% of your ad inventory has been filled with paid ads, while the remaining 20% has gone unfilled, representing a potential loss in revenue.

In this blog, we’ll explore the importance of ad fill rate, what influences it, and strategies to improve it to increase your ad revenue.

What is Ad Fill Rate?

Ad fill rate is calculated using the formula:

Fill Rate (%) = (Filled Ad Impressions / Total Ad Requests) × 100

For example, if a site generates 10,000 ad requests and receives 7,500 filled impressions, the fill rate would be 75%. Achieving a high fill rate means that your ad slots are actively generating revenue, while a low fill rate could indicate that some of your ad inventory is going unsold, costing you potential income.

Why Ad Fill Rate Matters

1. Revenue Maximization: A low fill rate means missed revenue opportunities, as available ad slots are not being filled with paying ads.
2. User Experience: Unfilled ad slots may lead to blank spaces, which can affect the aesthetics and user experience of your website or app.
3. Higher Ad Viewability: A good fill rate ensures ads are displayed consistently, increasing their chances of being viewed and interacted with by users.

Factors Affecting Ad Fill Rate

1. Geographical Location: Some regions have higher demand for ads than others, which affects fill rates. For example, fill rates are often higher in the U.S. and Western Europe due to more advertiser demand.
2. Ad Format and Size: Specific ad formats (e.g., video, native ads) and sizes may have varying demand. For example, video ads generally have higher fill rates than banner ads.
3. Seasonal Trends: Ad demand often fluctuates based on the time of year, with higher demand during the holiday season and lower demand during certain off-peak times.
4. Floor Price: Setting a high floor price can reduce fill rate, as fewer advertisers are willing to meet the minimum bid requirement.

Strategies to Increase Ad Fill Rate

1. Optimize Ad Placement and Sizes

Choosing the right ad placements and sizes can significantly improve your fill rate. Popular ad sizes like 300×250 and 728×90 often have higher demand. Place ads in viewable areas to increase the likelihood of advertisers bidding on your inventory.

2. Use Header Bidding
Header bidding is an advanced programmatic technique that allows multiple advertisers to bid on your ad inventory simultaneously before the ad server call. This increases competition and maximizes the chances of filling each ad slot, leading to improved fill rates and CPMs (Cost Per Mille).

With PubPower Header Bidding solution, we help publishers bid their ad inventory to over 30 SSPs and 3000 direct advertisers worldwide, making every impression appear on their websites valuable.

3. Set Realistic Floor Prices

If your floor price is too high, advertisers may not bid on your ad slots, leading to lower fill rates. Regularly monitor and adjust floor prices based on market demand, seasonal trends, and ad performance to maximize your fill rate.

4. Increase Geographical Targeting

Expand your ad demand by enabling global targeting. While certain regions may have lower CPMs, a filled ad slot is usually better than an unfilled one, especially for users from countries with lower ad demand.

5. Utilize a Mix of Ad Networks

Working with multiple ad networks allows you to tap into a broader pool of advertisers. Each ad network may have different demand sources and geographical strengths. Combining them increases the likelihood of filling all available ad slots.

6. Implement Frequency Capping

Frequency capping controls how often the same ad is shown to a user. By capping ad frequency, you prevent ad fatigue and increase the chances of more diverse advertisers bidding on your slots, helping maintain a high fill rate and better user engagement.

7. Use Waterfall Setup in Conjunction with Header Bidding

A waterfall setup prioritizes ad networks based on their historical fill rates and CPMs, serving as a fallback mechanism if header bidding doesn’t fill all slots. This hybrid approach maximizes both fill rate and revenue potential by using both header bidding and traditional waterfall methods.

8. Improve Site Speed and User Experience

Slow-loading sites can negatively impact ad load times and viewability, which may lead to unfilled ad slots. Use tools like Google’s PageSpeed Insights to optimize load times and improve the overall user experience, which can indirectly lead to higher fill rates.

9. Leverage Seasonal Demand

Advertiser demand spikes during certain times of the year, like the holiday season, Black Friday, or back-to-school months. Adjust your ad strategy during these periods to capture higher fill rates and maximize revenue potential.

You can check these tips to increase ad revenue in holiday season

10. Analyze and Adjust Regularly

Regularly monitor your fill rate performance and identify patterns or dips. Adjusting your ad strategy based on these insights—whether by changing ad networks, adjusting floor prices, or testing new formats—can lead to improved fill rates over time.

Can I Get 100% Ad Fill Rate?

A 100% fill rate might initially seem ideal, as it indicates that every ad request is being filled. However, it’s not necessarily the best outcome for a publisher’s revenue and user experience. Here’s why:

1. Ad Quality Concerns: To achieve a 100% fill rate, ad networks may need to accept lower-quality or low-cost ads just to fill the slots. This can lead to poor-quality ads being shown, which may decrease user engagement or trust in your site.
2. Lower CPMs: With 100% fill rate, your ad inventory may include ads with lower CPM (Cost Per Mille) rates. This means that while every slot is filled, the revenue from each impression could be lower than if you focused on higher-quality, higher-paying ads.
3. Ad Saturation and User Fatigue: When every slot is filled, users might experience ad fatigue, leading them to ignore or even block ads. This can reduce engagement and even lead users to avoid your site, negatively impacting long-term ad revenue.
4. Better Alternative: Many publishers aim for a balanced approach—high fill rate with high CPM—ensuring that most ad requests are filled but with quality ads that yield higher revenue per impression. A fill rate around 90-95% often represents an optimal balance where high-quality ads are prioritized without overloading every slot.

While a 100% fill rate may indicate that no opportunity is being missed, it is often more valuable to maintain a slightly lower fill rate that prioritizes ad quality, user experience, and higher CPMs.

Conclusion

Increasing ad fill rate is essential for publishers aiming to maximize their programmatic revenue. By understanding the factors affecting fill rate and implementing strategies such as header bidding, waterfall setup, and realistic floor prices, publishers can ensure their ad inventory is used to its full potential. Regular analysis and adjustments based on performance data are key to maintaining an optimal fill rate and maximizing revenue in the long run.

Optimizing for a high ad fill rate not only increases revenue but also contributes to a better user experience, as users are more likely to see diverse, relevant ads. For any publisher focused on driving programmatic success, boosting ad fill rate should be a top priority.