Why cpm matters
It is the price of attention in the auction you are buying in, and mostly reflects how much competition there is for your audience rather than how good your ad is.
What this looks like with real numbers
Your CPM rises from $9 to $15 over a quarter. Before blaming the creative, check whether the audience narrowed, whether you moved into a more competitive placement, and what month it is. Q4 CPMs rise for everyone because the auction fills with retail budget.
What it does not tell you
A rising CPM is not automatically a problem and a falling one is not automatically a win — cheap impressions in front of the wrong people are the most expensive thing in advertising.
The mistake people actually make
Chasing a low CPM by widening placements. Cheap impressions in front of the wrong people are the most expensive thing you can buy.
Questions, answered.
How do you calculate cpm?
(Spend ÷ impressions) × 1,000. The cost of a thousand impressions.
What goes wrong with cpm?
Chasing a low CPM by widening placements. Cheap impressions in front of the wrong people are the most expensive thing you can buy.
What does cpm not tell me?
A rising CPM is not automatically a problem and a falling one is not automatically a win — cheap impressions in front of the wrong people are the most expensive thing in advertising.
Change the creative, not the dashboard
The cost of a thousand impressions.