What is fill rate

Ad Fill Rate: Practical Tips for Increasing Revenue For Publishers

As an online publisher, you're likely familiar with the concept of ad fill rate. It refers to the percentage of ad requests that are filled with ads, and it's an important metric for measuring ad inventory utilization and revenue potential.

In this blog post, we'll discuss what an ad fill rate is, how it's calculated, and what a good fill rate looks like. We'll also explore some common reasons why your ad fill rate may not be at 100% and provide tips for optimizing it to increase your ad revenue.

What is Ad Fill Rate?

Ad fill rate is the percentage of ad requests that result in an ad being displayed on a publisher's website. It is an important metric for publishers because it reflects the efficiency of their ad inventory utilization. If the ad fill rate is low, it means that there is unsold ad inventory that could be generating revenue. Additionally, if an ad placement has a low viewability, advertisers won't want to buy its impressions because there is a low chance that users will see the impressions. On the other hand, a high ad fill rate means that the publisher is effectively monetizing their ad inventory.

How Is Ad Fill Rate Calculated?

Ad Fill Rate Calculate

Ad fill rate is calculated by dividing the number of ad impressions served by the number of ad requests made. The resulting percentage represents the number of ad requests that were successfully filled with an ad.


Here is the formula for calculating ad fill rate:

Ad Fill Rate = (Ad Impressions Served ÷ Ad Requests Made) x 100

For example, if a website had 1,000 ad requests and 800 of those requests were successfully filled with an ad, the ad fill rate would be:

Ad Fill Rate = (800 ÷ 1,000) x 100 = 80%

This means that 80% of ad requests were successfully filled with an ad. Ad fill rate can be calculated for a specific ad network, ad exchange, or across multiple sources, depending on the publisher's needs.

What Is A Good Ad Fill Rate?

The benchmark for a good ad fill rate varies by platform, ad format, and general inventory. Additionally, different ad networks and demand sources may have different fill rate benchmarks. This makes it difficult to give an exact number of what a good ad fill rate is. As a general rule of thumb, display ads typically have a higher fill rate than video ads.

However, it's important to note that ad fill rate should not be the only metric used to evaluate ad inventory utilization. For example, in some instances, it can be favorable to set higher price floors which might lower your fill rate but can give you higher CPMs nonetheless. Therefore, publishers should also consider other metrics, such as eCPM (effective cost per thousand impressions), which takes into account the revenue generated by each ad impression.

Reasons Your Ad Fill Rate Isn't 100%

Achieving a 100% fill rate can be challenging, and there are several reasons why a publisher may not be able to achieve it. Some of the most common reasons include:

Ad block usage
Ad block software prevents ads from appearing on a website, reducing the number of available ad impressions and ultimately lowering the fill rate. Our anti-adblock solution helps publishers to recover ad revenue lost due to ad block usage, see how this website saw an instant increase in recovered revenue with Snigel’s solution.

Ad quality
Poorly designed or irrelevant ads may deter users from clicking on them, leading to a lower click-through rate (CTR) and lower fill rate.

Lack of demand and website traffic
One common reason for a low fill rate is the lack of demand in the market. Ad inventory may not always be available, so ads may not be as common as publishers would like them to be. This can lead to lower ad fill rates and potential revenue loss.

To address this issue, publishers can explore solutions such as header bidding, which can help increase demand for ad inventory and boost fill rates.

Technical errors
Despite efforts to provide a seamless ad experience, technical errors can occur in the ad tech ecosystem. With the sheer volume of websites and ad networks, there is a higher risk of technical errors that can impact ad fill rates and revenue potential.

To avoid technical errors, publishers should pay close attention to ad verification processes and ensure that their ad tech functions properly. Regular monitoring and testing can help identify and resolve any technical issues.

High Floor Prices
Floor prices can push advertisers to pay more but it can also create more unfilled impressions. When setting floor prices, it's important to find the right balance by experimenting with different floors per GEO, unit, and device. Snigel's AI price floor tool automatically adjusts floors every hour based on these criteria.

Latency, or slow-loading ads, is another factor that can impact fill rates. When ads take too long to load, users may leave the page before the ad is displayed, leading to lower fill rates and lost revenue. You can check a page's latency with Google’s PageSpeed Insights tool.

To address latency, publishers should use lazy loading, asynchronous loading, and a lightweight header bidding solution like Snigel's AdEngine to ensure their ads load fast and achieve a high viewability score.

By addressing these common issues, publishers can increase their ad fill rates and maximize their revenue potential. Additionally, partnering with an experienced ad management company like Snigel can help ensure that technical issues are identified and resolved promptly while also providing access to advanced ad optimization solutions like header bidding.

At Snigel, we understand the challenges that publishers face when it comes to optimizing fill rates. That's why we offer a range of services to help publishers address these issues. Get in touch to find out how we can help your website.

Is 100% Fill Rate Good?

While a 100% fill rate may seem like the ultimate goal, it's important to consider the potential implications of achieving it. For example, filling every available ad impression with an ad can negatively impact the user experience by cluttering the website with too many ads. This can lead to users leaving the website and a drop in overall revenue.

It's also important to note that other metrics, such as click-through rate (CTR) and effective cost per thousand impressions (eCPM), are equally important to consider when evaluating the success of an ad campaign. A high fill rate but a low CTR or eCPM may indicate that the floor price for the inventory may be too high.

At Snigel, we work with publishers to find the right balance between fill rate and other metrics to ensure they achieve the highest possible revenue while maintaining a positive user experience. Get in touch to find out more.

Can Fill Rate Be More Than 100%?

It may seem counterintuitive, but in some cases, fill rate can actually exceed 100%. This phenomenon, known as overfilling, occurs when more ad impressions are served than there are available ad opportunities.

Overfilling typically happens when publishers work with multiple ad networks and ad exchanges, each of which may be able to fill some of the available ad inventory. By combining the demand from multiple sources, publishers can sometimes achieve a fill rate higher than 100%.

However, while overfilling may sound like a good thing, it can have some drawbacks. Here are some potential benefits and drawbacks of overfilling:


  • Higher ad revenue: With more demand for their ad inventory, publishers can potentially earn more revenue per impression.
  • Better ad targeting: By working with multiple demand sources, publishers may be able to deliver more relevant ads to their audience.
  • More diversified revenue streams: By spreading their ad inventory across multiple sources, publishers may be able to reduce their reliance on any one partner.


  • Ad quality issues: Overfilling can lead to a higher number of ads being displayed, which can negatively impact user experience if not managed carefully.
  • Ad latency: With more demand sources involved, there is a higher chance of ad latency or slow-loading ads, which can frustrate users and lower engagement.
  • Lower fill rate for specific ad networks: While overfilling can lead to an overall higher fill rate, some ad networks or exchanges may end up with a lower fill rate due to increased competition from other sources.

In general, overfilling should be approached with caution. While it can lead to higher revenue and better ad targeting, it can also have negative effects on user experience and specific demand sources. Publishers should consider their goals and weigh the potential benefits and drawbacks before pursuing overfilling as a strategy.

How to Increase Fill Rate

Improving ad fill rate is a top priority for publishers looking to maximize their revenue potential. Here are some practical tips for increasing fill rate:

Optimize Ad Placement and Targeting
Placing ads in strategic locations on your site and targeting them to the right audience can help increase the likelihood of ads being filled. For example, placing ads above the fold or near engaging content can increase visibility and user engagement with the ads.

Work with Networks That Have a 100% Fill Rate
Some ad networks, such as Google AdX, have a reputation for having high fill rates. Partnering with these networks can help ensure that a high percentage of ad requests are filled.

anti abdlock

Implement an Anti-Adblock Solution
Implementing an anti-adblock solution can help ensure that your ads are seen by all visitors to your site, regardless of whether they are using an ad-blocker or not.

Targeting ads based on your visitors' location can help increase your ads' relevancy and improve your fill rate.

Reduce Ad Latency
Slow-loading ads can lead to a poor user experience and lower engagement. By optimizing ad latency and reducing load times, publishers can improve their fill rate and user experience.

Implement Header Bidding
Header bidding is a programmatic advertising technique that allows publishers to offer their inventory to multiple ad networks simultaneously, increasing competition for ad placements and potentially leading to higher fill rates.

By following these tips, publishers can increase their fill rate and maximize their revenue potential. At Snigel, we specialize in helping publishers optimize their ad inventory and achieve the most sustainable fill rates. Contact us today to learn more about how we can help you optimize your ad inventory and increase your ad fill rate.


In conclusion, ad fill rate is an important metric for publishers to monitor and optimize in order to maximize their revenue potential. While achieving a 100% fill rate may seem desirable, it's important to find the right balance between fill rate and other metrics in order to maintain a positive user experience and maximize revenue.

Common reasons for not achieving a 100% fill rate include ad block usage, ad quality issues, and website traffic. To improve ad fill rate, publishers can implement practical strategies such as optimizing ad placement and targeting, implementing an anti-adblock solution, geo-targeting, reducing ad latency, and implementing header bidding.

At Snigel, we offer full-service ad management services to help publishers optimize their ad inventory and achieve higher ad fill rates. Get in touch with our ad ops experts to find out how.

Remember, optimizing your ad fill rate is just one part of a comprehensive ad strategy. By focusing on user experience and implementing best practices across your site, you can achieve a better balance of fill rate, CTR, and eCPM, leading to higher overall revenue and a happier user base.

About the Author

Ira is Snigel's Head Of Marketing. She supports our team and publishers by creating awesome guides on the latest adtech trends. Ira's background is in software development, communications, and media.


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