CPM calculator
Calculate the cost of one thousand ad impressions from spend and delivery.
Last updated
Written by Madly editorial
01 / Your inputs
Run the numbers
Example figures are filled in so you can see a result straight away. Replace them with your own. Results update as you type; no data is sent or saved.
Total media spend in the same currency as your revenue.
Number of times the ad was shown.
02 / Calculation
Cost per thousand impressions
Calculated result
£10.00
Unit: £/1,000 impressions
Formula
CPM (£/1,000 impressions) = ad spend (£) ÷ impressions × 1,000.
How to read this
A higher CPM can coexist with better sales if the audience converts more often. Look at results further down the funnel.
Assumptions
Impressions count ad deliveries, including repeats to the same person. Spend and impressions must cover the same period.
How to use this tool
- Find total spend and total impressions for the campaign or ad set.
- Enter them and read the cost per thousand impressions.
- Compare CPM between audiences or placements to see where reach is cheaper.
- Pair it with CTR, because a cheap CPM with few clicks is not cheap reach.
Worked example
Illustrative example: £240 for 20,000 impressions gives £12 CPM.
What this measures
CPM is a delivery-cost measure, not a measure of distinct people reached or orders won.
Formula and units
CPM (£/1,000 impressions) = ad spend (£) ÷ impressions × 1,000.
Assumptions and review notes
Impressions count ad deliveries, including repeats to the same person. Spend and impressions must cover the same period.
A higher CPM can coexist with better sales if the audience converts more often. Look at results further down the funnel.
CPM measures the price of attention, not the result. It rises when more advertisers compete for the same people, such as before major sales periods, and it can fall in quieter months. A higher CPM is not automatically bad if the audience is more likely to buy. Compare your own CPM over time and by audience rather than against a general average.
- Seasonality and sale events.
- Audience size and targeting precision.
- Placement and format.
- Ad quality signals used by the platform.
- Reading a low CPM as an efficient campaign.
- Comparing CPM across platforms with different impression definitions.
- Forgetting that CPM combined with CTR drives CPC.
- Changing audience and creative at once, then blaming CPM.
A closer look
Common questions.
- What is CPM?
- CPM is cost per mille, the cost of 1,000 ad impressions. It is spend divided by impressions, multiplied by 1,000.
- Why does CPM change so much?
- It reflects auction competition, so it moves with season, audience and placement.
- Is a high CPM bad?
- Not necessarily. If the people reached buy more often, a higher CPM can still be profitable.
- How is CPM linked to CPC?
- CPC equals CPM divided by 1,000 and then divided by CTR as a decimal. A higher CTR lowers CPC at the same CPM.
- Should I optimise for CPM?
- Rarely. Optimise for profitable purchases and use CPM to understand why costs moved.