Work out CPM (cost per 1,000 impressions) from your spend and impressions, or find the total cost or impressions from a CPM.
Results are estimates for planning. Check the figures before you make a financial or health decision.
How to calculate CPM
Divide the ad spend by the number of impressions, then multiply by 1,000:
CPM = ad spend ÷ impressions × 1,000
The M stands for the Roman numeral for one thousand. To find the cost of a campaign, multiply impressions ÷ 1,000 by the CPM. To find the impressions a budget buys, divide the budget by the CPM and multiply by 1,000.
Worked example
Using the default values in the calculator above:
| Input | Value |
|---|---|
| What do you want to find? | CPM (cost per 1,000) |
| Ad spend | 800 |
| Impressions | 250,000 |
| CPM | 4 |
| Result | Value |
|---|---|
| CPM | 3.2 |
| Ad spend | 800 |
| Impressions | 250,000 |
| CPM | 3.2 |
| Impressions per 1 spent | 312.5 |
What is a good CPM?
CPM depends on the platform, audience, format and season. Narrow, high-value audiences cost more, and video usually costs more than static display. Prices also rise in busy periods such as the weeks before Christmas. Compare CPMs for the same type of audience and placement, and look at results beyond reach.
Tips and common mistakes
CPM buys visibility, not action. If your goal is sales, a low CPM can still lead to a high cost per sale. Check CTR and conversion rate as well.
Know what counts as an impression. Platforms define it differently, for example whether a video must be partly viewed.
Publishers use the same maths from the other side: RPM is revenue per 1,000 impressions or page views. The AdSense and ad revenue calculator covers that.
Frequently asked questions
What does CPM mean in advertising?
Cost per mille, meaning the cost per 1,000 ad impressions.
Is CPM or CPC better?
Neither is better in general. CPM suits awareness goals, while CPC and CPA suit traffic and sales goals. Choose the model that matches what you want to pay for.
How do I convert CPM to CPC?
Divide the CPM by 1,000 and then by your CTR as a decimal. For example, a 4 CPM at 1 per cent CTR is 0.40 per click.
What is eCPM?
Effective CPM: the revenue or cost per 1,000 impressions worked out from any pricing model, which lets you compare different models.