CPM is the cost of 1,000 ad impressions: divide the campaign cost by the impressions and multiply by 1,000. A $2,500 campaign with 400,000 impressions has a CPM of $6.25. Turn the formula around to get the budget for a target reach, or the impressions a budget buys.
Four calculations in one tool
- CPM: cost ÷ impressions × 1,000.
- Budget: CPM × impressions ÷ 1,000, for a target number of impressions.
- Impressions: budget ÷ CPM × 1,000, for what a budget buys.
- CPC to CPM: CPC × CTR × 1,000, to compare a cost-per-click offer with a CPM one.
What is CPM?
CPM, or cost per mille, is what an advertiser pays for 1,000 impressions of an ad. Mille is Latin for thousand. An impression is one showing of the ad, whether or not anyone clicks. CPM is how reach is priced and compared across channels such as Meta, LinkedIn, display and video.
Impressions are not people. One person can see an ad several times, so reach counts people and frequency is impressions divided by reach. A low CPM with a high frequency can mean the same few people see the ad again and again.
How to calculate CPM
Take the cost
What the campaign spent on media, from the ad platform. Leave fees out unless you want them in the comparison.
Take the impressions
The number the platform reports for the same dates and the same campaigns.
Divide, then multiply by 1,000
$2,500 ÷ 400,000 = $0.00625 per impression. Times 1,000, that is a $6.25 CPM.
In Excel or Google Sheets
With the cost in A2 and impressions in B2, CPM is =A2/B2*1000. For the budget a target needs, use =CPM*impressions/1000. For the impressions a budget buys, use =budget/CPM*1000.
What is a good CPM?
There is no single good CPM. It moves with the channel, the audience, the format, the season and the auction. A narrow B2B audience on LinkedIn costs more per impression than a broad consumer audience on Meta, and can still be cheaper per customer.
Work out the CPM you can afford
Start from what a customer can cost. Maximum CPM = target cost per acquisition × conversions per impression × 1,000. If a customer can cost $400 and one in 20,000 impressions becomes a customer, you can pay up to $20 per 1,000 impressions.
CPM vs CPC vs CPA: which to use
| Model | You pay for | Use it when | Watch out for |
|---|---|---|---|
| CPM | 1,000 impressions | Reach matters, or you expect a strong click rate | Paying for views nobody notices |
| CPC | A click | You want visits to a page and clicks are a fair sign of interest | Clicks that never convert |
| CPA | A conversion, such as a lead or a sale | Conversion tracking is reliable and volume is steady | Cheap conversions of low quality |
To compare a CPC offer with a CPM one, convert it: effective CPM = CPC × CTR × 1,000. At a $2.40 CPC and a 0.6% click-through rate, the effective CPM is $14.40. If the CPM offer is lower and the audience is the same, impressions are the cheaper buy.
CPM bidding in new channels
New ad channels often start with CPM, because it is the simplest thing to sell before click and conversion data exist. OpenAI first sold ChatGPT ads on a CPM basis and added cost-per-click bidding in May 2026. Its developer documentation also describes bidding for conversions.
For a first test in a new channel, set a CPM you can afford from your own cost per customer, and judge the test by the cost per qualified lead, not the CPM.
CPM questions
How do I calculate my CPM?
Divide what the campaign cost by its impressions, then multiply by 1,000. $900 for 150,000 impressions is a $6 CPM.
How much does CPM cost per 1,000 views?
CPM is the price per 1,000 impressions, so a $6 CPM means $6 for every 1,000 times the ad is shown. The rate itself depends on the channel, the audience and the auction.
What does a $20 CPM mean?
You pay $20 for every 1,000 impressions, which is 2 cents per impression. A $1,000 budget at a $20 CPM buys 50,000 impressions.
What’s a good cost per impression?
One your cost per customer can carry. Work back from the customer: target cost per acquisition × conversions per impression × 1,000 is the most you can pay per 1,000 impressions.
How do I calculate cost per impression?
Divide the cost by the impressions. $2,500 ÷ 400,000 is $0.00625 per impression. CPM is the same number times 1,000.
Formulas and sources
- Formulas
- CPM = cost ÷ impressions × 1,000. Budget = CPM × impressions ÷ 1,000. Impressions = budget ÷ CPM × 1,000. Effective CPM = CPC × CTR × 1,000.
- Checked
- 3 November 2026. Ad platforms change their buying options. The date shows when the sources were last read.
- What this page does not claim
- Typical CPMs by channel. We publish benchmarks only with a named source and a date.
2 sources: OpenAI. Checked
Sezemov, M. (2026). CPM calculator. Wonderflow. wonderflow.agency/tools/cpm-calculator/
