What is Ad Fill Rate? How to Calculate it?

Brock Munro
December 22, 2021
April 22, 2024
What is Ad Fill Rate? How to Calculate it?

With almost 252,000 websites being created each new day, it is no wonder that publishers struggle to get high fill rates for each ad request they place. There are many factors that can frustrate publishers in their bid to sell and buy ad units.

For instance, with the increased number of available websites and limited users, the demand for publishers is quickly diminishing.

The good news is that you can solve your ads fill rate challenges by reaching out to Publift. We specialize in programmatic advertising and ensuring that you get maximum income from all the ads requested from your ad server.

What is the Ad Fill Rate?

Ads Fill Rate definition

The ads fill rate is the percentage number of ads served divided by the total number of ad requests that the server makes. Simply put, the add fill rate is one of the simplest ways to tell whether or not your ad request on the server has been a success.

How to Calculate Ad Fill Rate?

How to Calculate Ad Fill Rate

Calculating the ad fill rate is not as difficult as it may sound. You can calculate your ads fill rate by dividing the total number of ad impressions by the total number of ad requests and getting its percentage.

Impressions are counted each time the ad appears on your site, and hence revenue is allocated to you.

You should know that the fill rate is not directly determined by the number of ads you receive but more by the number of times viewed. This means that you may receive more ads on your website but have a constantly low fill rate if the new ads do not get viewed.

Can You Achieve a 100% Ad Fill Rate?

While you may aim at attaining a 100% ad fill rate, it is not an easy feat to achieve. Every advertiser is particular about getting their ads across to their target audience. So they will pick publishers that best suit their interests. This, in turn, means that not all your ad calls will receive placements.

However, you can get higher fill rates over time by employing a number of strategies that are proven to increase your average fill rate and maintain them at a high point.

You can work your way through ads campaigns and attain a 100% fill rate if you consistently stick to the digital advertising industry best practices for publishers.

Reasons Your Fill Rate Isn't 100%

You have probably been in the publishing business for a while now and have a good sense of the fill rate and how it generally works. However, you can't seem to shake off the lower fill rates plaguing your website.

Here are some of the reasons why your ad fill rates are plummeting downwards and not on the rise;

Lack of Demand

As sad as it may sound to any aspiring publisher, ads are not as common to come by as you may wish. That is one of the reasons why your ads fill rate may be worryingly low.

With the low demand in the market, it is best to look for solutions to boost your fill rates. For instance, you may want to consider header bidding, which may offer you a solution to your low fill rate and fill the gap in demand.

Technical Errors

While most networks strive to offer the best ad experience, few actually can boast of impeccable technologies. In a world where a single network can deal with over a thousand websites at a time, there is huge room for technical errors.

Sadly, such errors pose a risk to your potential revenue. To avoid such trouble, pay keen interest in processes such as ad verification and the ad tech that is in place for your website.


Another common cause of lower fill rates in a website is latency. Latency can delay ad rendering in user devices. As a result, the ads will take much longer than necessary to load, causing customers to leave your page before the ads loads.

Advertisers often turn down requests from websites with latency issues and instead use a different publisher for their ads.

To beat latency on your page, it is best to stick to manageable ad sizes that cause your page to have an extended load time.


Ad rendering is essential if you are to increase your overall fill rate. For this reason, you need to be careful to get browsers and devices that are compatible with current versions.

Be keen to use formats and ad sizes compatible with your target audience's devices and their general demand.

Reporting Discrepancy Between Ad Request and Ad Impressions

While your site's analytics will count an ad impression when the page starts to load, ad servers only consider the impressions after the page fully loads. The user is long gone before the load time elapses in some instances. This, in turn, will cost you the revenue that you think you have earned.

In such cases, you will need to consider these mitigation tips for your website.

Ad Blockers

Plenty of adblockers today work by blocking the ad network while they should be blocking ad calls. This, in turn, allows ad requests but not the ads themselves. Luckily, this is not a problem you cannot solve! You can even recover your lost revenue from adblockers.

But is 100% Ad Fill Rate Ideal?

No. While 100% may seem like the ultimate fill rate to attain, it is far from ideal. This is because 100% fill rates may sometimes translate to low-quality ads. That is why Google Adsense uses Adbalance to ensure you get just enough ads without sacrificing the ad quality or the ad impression.

How do I Increase the Ad Fill Rate?

So now that you know why your ads fill rate is low and that you can improve it, here is what to do to get a high supply of ads for your website.

Subscribe to Networks with 100% Fill Rates

The first step to attaining a higher ad fill rate is realizing that you need help.

While most ad networks aim at simply giving you a good fill rate, you should aim at one that promises 100% fill rates. This way, you stand to increase your revenue within no time.

Optimize Ad Fill Rate with Multiple Ad Networks

When choosing your ideal network, never limit yourself to just one network. The best way to go is through multiple ad networks. This way, you can contact each of them and compare the tips they share and their ad campaigns.

The most important thing to note while choosing your ad network is carefully considering their rates before selecting any network.

Ad Blocking

Ad blocking is probably one of the most lethal threats to your revenue. The worst thing about it is that no publisher (no matter how strictly they adhere to the ad placement policies in place) is entirely safe from adblockers.

Luckily, there are several strategies you can employ to navigate the adblockers hurdle. At Publift, we can help you ensure that no ad blocker holds you back from your possible revenue.


As you try to optimize your fill rate, you will want to focus on a particular target audience as this will give you a high fill rate and a steady potential revenue at the same time.

Ensure that you research your target market and focus on the countries in which your potential audience is located.

This way, you can choose an ad network that specializes in that country or region and increase your income in the long run.

What are Ad Networks?

If you are new to publishing, you must be wondering what these networks are and how they work to ensure you achieve that high fill rate.

Ad networks act as middlemen between advertisers and publishers. They do this by collecting ad inventory of ad slots, ad calls, ad units, and requests.

The information is then sold to publishers and advertisers. The networks then take part of the ad revenue as their payment.

Every Ad network has its servers which they use to relay ads to a publisher's site. They do this using codes that call the ads.

Typically, the networks are in charge of the entire ads campaign, ensuring everything runs smoothly, not just for the advertisers but also for the publishers. They are also at liberty to negotiate terms revolving around the add impression, targets, ad placements, and the cost per impression (CPM).

How to beat Adblockers

While Ad blockers are a bummer, there are many factors that you can put into place to ensure you circumnavigate them and achieve a higher fill rate for your site.

  • Focus on native advertising
  • Request your users to turn off ad blockers
  • Advertise ethically
  • Have your users in mind

Bring Us on Board

Optimizing your ad fill rate does not always have to be complicated. You can let our professional team take care of it as you focus on creating your content and bettering your site.

If you’re making more than $2,000 in monthly ad revenue, contact us today to learn more about how Publift can help increase your ad revenue and best optimize the ad space available on your website or app.

Grow with us

Grow your business with a sustainable, long term partnership. If you're making more than $2,000 in monthly ad revenue, contact us today to boost your revenue with our all-in-one solution.
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