How Seasonality Affects CPMs

By Sortable |
March 31, 2016

Topics: Blog, Sortable


Ad Ops & Digital Publishing News - Sortable

As a new quarter approaches, you’ve probably noticed that your CPMs are starting to drop. And you might be wondering why. Depending on the time of year, CPMs and fill rates can fluctuate significantly. While some verticals are impacted more than others, it’s important to understand how seasonality affects CPMs.

Advertisers tend to increase their spend in line with significant events - think Black Friday, Christmas, Super Bowl Sunday - and publishers will see corresponding increases in CPMs. Outside of major events, brands tend to spend the least in the first month of a quarter, and the most in the last month. So, as we leave Q1, you probably noticed that you experienced the lowest CPMs of the quarter in January, and the highest in March. Additionally, advertisers spend less in the summer months (July, August) but CPMs pick up again in September.

To help show how seasonality affects CPMs, we’ve compiled some data from 2015 to show how CPMs fluctuate month over month, quarter over quarter, and what you can expect to see in the days leading up to and immediately following the start of a new quarter.

Screen Shot 2016-03-30 at 3.49.54 PM

First, let’s look at CPMs month over month. You’ll notice that CPMs increase fairly steadily after January, with slight drops in April, July, August and October. As noted above, campaign spend is scaled back during the summer months, and it’s normal to experience a dip in CPMs in the first month of a new quarter.

Our 2015 data shows that September, October, November and December are the strongest- performing months, while January, February, March and April experience significantly lower CPMs than the rest of the year.

CPMs MbyM transparent

Now, let’s look at quarterly performance. You’ll see that, overall, CPMs increase steadily through Q3, with a significant jump in Q4. As previously mentioned, even with low campaign spend in July and August, Q3 outperforms Q2 as CPMs jump in September.


As we close out a quarter, it’s useful to note that it’s normal to see a drop in CPMs in the week leading up to and the week following a new quarter. This is largely because quarterly campaign budgets are depleted, impacting CPMs and fill rates.

CPMs two week view

It can take 7-10 days to start seeing CPMs performing as expected, so the temporary decrease isn't a cause for concern.

Your experience throughout the year may be different - not all verticals are equally impacted by seasonality. But if your vertical is one that is more sensitive to seasonal fluctuations, you can refer to the charts above to help forecast revenue on a quarter by quarter or month by month basis.

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