Fill Rate: Not the End Goal, But a Tool That Can Help You Get There

It’s no secret that Mediavine doesn’t fill ads at a 100% rate. We’ve even been so bold as to say that 100% fill rate is actually a bad thing.

Yet the subject of fill rate and how to increase it is still a frequent — if often misunderstood — topic in our support channels.

Perhaps it’s time to reframe the discussion: 

What if we looked at fill rate not as an objective, or end goal, but rather as one of many tools to analyze ad performance and site health?

Fill rate is a useful metric, to be sure. It can tell you many things about your website and how advertisers are reacting to it.

For example, if you notice that fill rate has dropped dramatically, this could be for a number of reasons and should prompt certain questions.

Did the majority of traffic shift from English-speaking countries to non-English speaking countries?

Advertiser demand to non-English speaking countries and users is always lower, simply because there is a smaller pool of brands trying to reach those demographics. 

As a result, fill rates will always be lower with traffic coming from such countries relative to the U.S. and other English-speaking counterparts.

Additionally, a sudden shift to international traffic puts advertisers on high alert. 

Suspicious that something amiss may be causing this traffic spike, such as an increase in bot or other invalid traffic, they may pull out of the auction altogether.

What time of year is it? 

I’ve written about ad revenue seasonality at length — perhaps you’ve seen my posts in our Facebook group coinciding with certain times of year.

Just as consumer spending ebbs and flows throughout the year, the calendar will impact fill rates and CPMs for online advertising as well.

It’s not just the end of the month or the quarter where we see peaks and valleys, either. We see drop-offs in fill rates after all holidays as advertising demand drops. 

For example, we typically see a slight decline after Mother’s Day and Father’s Day, with fewer consumers in the market for the perfect gift for mom or dad.

Are your popular posts brand safe?

Words obviously matter to your readers, but also to advertisers. The content of your posts helps determine if your post is brand safe. 

Advertisers want assurance that their ad is not only reaching their target audience, but placed next to no material that could be deemed offensive. 

My favorite example of this happened last year, regarding a publisher who posted some great content surrounding relationship advice. 

It was formatted beautifully and seemed to check all the boxes for success, yet fill rates were very low for no immediately obvious reason.

Then we noticed that the content contained the word “sex.”

That’s it. Not out of the ordinary on a blog about strengthening relationships, and not used in an inappropriate context whatsoever. Just the word.

Suspecting that this could be the cause of the lower fill rate, we worked with the publisher to swap out “sex” with (wait for it) “make love.”

We saw an immediate boost in fill rate — and earnings to go with it.

The moral of the story is that advertising algorithms are incredibly intelligent, just not intelligent enough to figure out in what context words are being used.

This example is a great reminder to always be mindful of the words used in your posts, even if your intent isn’t salacious or controversial.

Make CPM the Primary Focus

While fill rate helped us find the issue in the above example, I’m going to do some quick math to illustrate why you should primarily focus on CPMs, not fill rates. 

Let’s say you took 10,000 impressions filled at 100%. 

In order to fill every single impression, we had to mix in lower quality ads resulting in lower CPMs, bringing the average CPM down to $0.50. 

In other words: 10,000 impressions * $0.50 CPM / 1000 = $5.00 in revenue

Now, let’s take that same 10,000 impressions and only fill 70% (still a great fill rate). By focusing on quality over quantity, our average CPM is $1. 

In other words: 7,000 (70% of 10,000) impressions * $1 CPM  / 1000 = $7.00 in revenue

This plainly illustrates that the goal should be a higher CPM, not a higher fill rate. With quality traffic and quality CPMs, quality fill rates will follow. 

Mediavine has numerous measures in place to help increase CPM, such as lazy loading to increase viewability, sticky units, price flooring and more. 

How to increase CPMs

What can you, as a publisher, focus on to help increase CPMs?

Increase your site speed.

It wouldn’t be a proper Mediavine blog post if increasing site speed wasn’t mentioned at least once, and for good reason. 

Faster websites see higher viewability of the ad units, and higher viewability leads to higher CPMs. Every. Single. Time.

(We’ve compiled all of our pagespeed resources into one handy guide, putting lightning speed at your fingertips.)

“Use your words.”

I’ve used this phrase often as a parent to two young kids, and believe it or not it’s also relevant here. 

Focus on writing good, clean, family-friendly content. (Here are 4 tips for producing higher quality content.)

Advertisers do not want their brands placed next to anything that could be controversial in any context, even if that’s not the post’s intent.

Focusing on writing clean content may be an extra step, but it works. Advertisers will focus on delivering high paying ads to your site in return.

Diversify your traffic stream.

We see the best ad performance with a mix of traffic sources. A site with high traffic coming from a single source, like Pinterest, will never see CPMs as high as a site whose traffic comes from a variety of sources. 

At Mediavine, we always recommend focusing on strong SEO, which results in increased organic traffic. We’ve talked about SEO a ton on the blog, from 3 action items that will result in organic traffic growth to our SEO resources guide, so we’ve got you covered.

Be GDPR Compliant.

Traffic from across the pond can still monetize at high CPMs, but only if you are GDPR compliant. Ensuring your site’s GDPR compliance allows advertisers to target sites with “personalized” ads — targeted to users based on their browsing habits.  

Mediavine offers its own consent management platform available to its publishers. Here are step-by-step instructions for how to implement our CMP on your site.