CPM Calculator
CPM $3.00
How do you calculate CPM?
CPM is what a thousand impressions cost. It is the figure you compare when advertising is priced by appearance rather than by click.
- Enter what you spent and how many impressions it bought. Both figures have to cover the same campaign and the same window, or the answer describes nothing.
- Divide the spend by the impressions. That gives what one impression cost, which is usually a fraction of a cent and hard to read.
- Multiply by a thousand, because CPM prices a thousand appearances at a time.
- To work back to a spend or to a number of impressions, change what the widget solves for and leave that field empty.
One relationship, three rearrangements
Two of the three figures are always enough; the third is whatever the other two make it. The worked column runs each line on real figures, so the spend row shows what a $10.00 CPM costs over fifty thousand impressions without you having to rearrange anything.
| Solve for | The line | Worked |
|---|---|---|
| CPM | CPM = cost / impressions x 1,000. | $1,200 over 400,000 impressions is $3.00 |
| Spend | Cost = CPM x impressions / 1,000. | a $10.00 CPM over 50,000 impressions is $500.00 |
| Impressions | Impressions = cost / CPM x 1,000. | $1,200 at a $3.00 CPM is 400,000 impressions |
Worked Example: $1,200 over 400,000 impressions
The CPM is $3.00. A $1,200 spend over 400,000 impressions is a CPM of $3.00.
$1,200 ÷ 400,000 × 1,000 = $3.00
Four hundred thousand impressions is four hundred blocks of a thousand, and $1,200 spread over four hundred blocks is $3.00 a block. Working in blocks rather than in single impressions is the reason the figure is readable at all.
What Does CPM Not Tell You?
An impression is not a person
One person who sees the same advertisement six times has produced six impressions. Reach counts people and frequency counts how often each one saw it; CPM counts neither, so two campaigns with the same CPM can reach very different audiences.
A served impression is not a seen impression
Most measurement counts an impression when the advertisement is served, and a served advertisement can sit below the fold for its whole life. Viewability is reported separately where it is reported at all, and CPM does not include it.
What the price does not say
A low CPM buys more appearances for the money and nothing else. Whether those appearances were worth having is a question about who saw them and what they did next, and the answer to that lives in your own results rather than in this figure.
Frequently Asked Questions
What does CPM stand for?
CPM is cost per mille, the cost of one thousand impressions; an impression is one appearance of the ad, not one viewer and not one click.
How do you solve for the spend or the impressions instead?
Change what the widget solves for, then fill the other two fields and leave the third empty. The table above gives the rearranged line for each of the three, so you can check the answer by hand before you commit a budget to it.
Is a $10 CPM good?
CPM tells you what a thousand impressions cost and nothing about whether they were worth buying; this page publishes no benchmark, because CPM varies by channel, format, country, season and targeting.
What is the difference between CPM and CPC?
CPM prices appearances and CPC prices clicks; the click-through rate connects them, so a $3.00 CPM at a 1 percent click-through rate is a $0.30 cost per click.
The rest of the site is on the other tools on iToolHub.