CPM calculator (cost per thousand impressions)
What it costs to reach a thousand impressions with your ad spend.
Calculator inputs
Results
Enter your values and press “Calculate” to see the result.
In short
- What it calculates
- What it costs to reach a thousand impressions with your ad spend.
- Formula used
CPM = cost ÷ impressions × 1,000- Example
- £600 spent for 150,000 impressions:
CPM calculator
CPM is the common currency of brand advertising: what it costs for a thousand people to see the ad.
It lets you compare very different media with a single figure.
How it works
Total spend is divided by impressions and multiplied by a thousand. The result also shows how many impressions each currency unit buys.
Formula
CPM = cost ÷ impressions × 1,000
Worked example
£600 spent for 150,000 impressions:
CPM: 600 ÷ 150,000 × 1,000 = £4.00
Each pound buys 250 impressions.
Explanation
CPM measures reach, not results
Cost per thousand impressions tells you what you pay to appear, not to persuade. It is a useful metric for awareness campaigns, where the goal is for many people to see the brand, and fairly useless for judging direct response campaigns, where cost per acquisition is what matters.
Impressions are not people
A thousand impressions can be a thousand people seeing the ad once, or a hundred people seeing it ten times. Average frequency is the missing figure, and without it CPM does not say how many people you actually reached. High frequency also causes ad fatigue and sinks performance.
What makes CPM expensive
Narrow targeting reduces available inventory and pushes the price up. Competing for high-demand audiences, such as professionals in specific sectors, does too. And seasonality is brutal: the weeks before Christmas or Black Friday multiply the cost of the same slots.
Viewability
A counted impression has not always been seen. Industry standards consider an ad viewable when at least half its pixels appear on screen for a minimum time. A cheap CPM with low viewability is expensive in reality.
Frequently asked questions
CPM or CPC?
CPM makes sense for awareness campaigns where reach is the goal. CPC fits better when you are after visits or sales.
Impressions or people reached?
They are not the same: one person may see the ad several times. To measure people you need reach and frequency.
Is a thousand impressions a thousand people?
Not necessarily. It can be fewer people seeing the ad several times. Average frequency is what tells them apart.
Why does CPM rise in November?
Seasonality: competition for the same slots spikes before Black Friday and Christmas, and auction prices rise with it.
Need to calculate something else?
These tools are often used alongside this calculator.
CTR
Percentage of clicks over impressions for ads, emails or search results.
ROAS
How much revenue each unit invested in advertising brings back.
Conversion rate
The percentage of visits that turn into sales or sign-ups.