Free tool
CPM Calculator
CPM is what you pay for a thousand impressions. Fill any two of spend, impressions and CPM below, and the third is worked out for you.
Fill any two
The third is worked out for you. Leave blank whichever one you are trying to find.
Cost per thousand impressions. Fill this one in when you are planning against a target rate rather than reporting on a finished campaign.
Your numbers
CPM
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Ad spend
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Impressions
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Cost per impression
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The formula
CPM = (ad spend / impressions) x 1000
Shares the numbers you entered, not your data. Everything is in the link itself.
What is CPM?
CPM is cost per mille, the price of one thousand impressions. It is how media has been sold since long before anyone bought an ad online, and it survives because it is the only figure that compares one placement against another before anybody clicks anything. Meta, Google, TikTok, YouTube and every programmatic exchange report it.
What it measures is the cost of attention, not the value of it. That distinction is the whole reason this page has a second half.
The formula, all three ways
CPM = (ad spend / impressions) x 1000
Ad spend = (CPM x impressions) / 1000
Impressions = (ad spend / CPM) x 1000
Most CPM questions are planning questions rather than reporting ones, which is why the calculator above solves in whichever direction you leave blank. You usually know two of the three and want the third.
A worked example
A campaign spends $2,000 and serves 400,000 impressions.
CPM = ($2,000 / 400,000) x 1000 = $5.00
Cost per impression = $2,000 / 400,000 = $0.0050
Run it the other way and the same numbers answer a planning question. At that $5.00 CPM, a $3,000 budget would buy ($3,000 / $5.00) x 1000 = 600,000 impressions.
Why a low CPM is not the goal
CPM is the easiest metric in the account to improve and one of the least useful to improve on its own. Widen the targeting, drop into cheaper placements, and the number falls immediately. Nothing about the business has changed except that you are now paying less for people who were always less likely to buy.
The number is doing its job when you read it as a component. Your cost per click is your CPM divided by your click-through rate times ten, so a creative that lifts CTR from 0.8% to 1.2% cuts your CPC by a third while the CPM sits exactly where it was. Check that with the CPC calculator and the CTR calculator, which take the same three inputs.
What actually moves your CPM
Who else wants the same people
CPM is an auction price. The same audience costs more in the run-up to Christmas than it does in February, and that has nothing to do with your account.
How narrow your targeting is
A smaller pool costs more per thousand. Sometimes that is worth paying and sometimes it is not, which is a question about your CPA rather than your CPM.
Which placements you allow
Feed, Stories, Reels and the audience network are priced very differently. Leaving placements on automatic hands that decision to the platform.
How people respond to the creative
Platforms discount ads people engage with, so a genuinely good ad is often cheaper to serve than a dull one aimed at the same audience.
Use this calculator on your own site
Free to embed and free to cite, no attribution deal needed. Writers, agencies and course authors are welcome to drop the calculator straight into a post, and a credit link back is all we ask.
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Frequently Asked Questions
What is CPM?
CPM is cost per mille: what you pay for one thousand impressions. It is the standard way media is priced across Meta, Google, TikTok, YouTube and programmatic display, which is why it is the number you compare a media owner against rather than clicks or sales. The formula is CPM = (ad spend / impressions) x 1000.
How do I calculate CPM?
Divide your ad spend by the impressions you received, then multiply by one thousand. A campaign that spent $2,000 and served 400,000 impressions has a CPM of ($2,000 / 400,000) x 1000 = $5.00. The calculator above also runs it backwards, so you can enter a CPM and a budget to get the impressions it buys.
How many impressions will my budget buy?
Divide your budget by the CPM and multiply by one thousand. At a $12 CPM, a $3,000 budget buys ($3,000 / $12) x 1000 = 250,000 impressions. Enter the CPM and the spend above and the tool solves for impressions, which is the version of this question most people actually have while planning a buy.
What is a good CPM?
There is no single good number, and anyone quoting one without naming the platform, the country, the audience and the month is guessing. CPM is set by how many other advertisers want the same people at the same time, so it moves with the auction: the same audience costs more in November than in February. Compare your CPM against your own previous months and against your other campaigns, not against a benchmark from someone else's account.
Is a lower CPM always better?
No, and this is the mistake the metric invites. CPM only prices attention, it says nothing about whether the attention was worth buying. Broad, cheap placements routinely deliver a low CPM and no sales, while a tightly targeted audience costs more per thousand and pays for itself. Read CPM next to your CPA or ROAS, never on its own.
What is the difference between CPM and CPC?
CPM is the cost of a thousand impressions, CPC is the cost of one click. They are connected by your click-through rate: CPC = CPM / (CTR x 10). A creative that lifts CTR lowers your CPC without your CPM moving at all, which is why creative is usually the cheaper lever of the two.
Do I need an account?
No account, no email, no credit card. Nothing you type is sent anywhere: the arithmetic runs in your browser.
The CPM is the auction. The creative is yours.
You do not control what an impression costs, and you do control what it carries. Selzee reads your reviews, comments and post results, then briefs and builds the next round of ad creative from what your own customers said, so the ads you serve at that CPM are the ones worth serving.
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