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Free tool

CPM impression calculator

Work out how many impressions a budget buys, what a campaign will cost, or the CPM you're actually paying. Enter any two of the three and the calculator solves for the third instantly.

Solve for

Total budget or amount spent

Cost per 1,000 impressions

Shorthand works: type 400k or 1.2m for impressions. Any currency works as long as spend and CPM use the same one.

Impressions
400,000

$5,000.00 ÷ $12.50 × 1,000 = 400,000 impressions

Cost per impression
$0.0125
Per 1,000 impressions
$12.50
The CPM formula

One formula, three ways to use it.

CPM stands for cost per mille, Latin for thousand, so it is the price of 1,000 ad impressions. Spend, CPM, and impressions are tied together by a single identity. Rearrange it to solve for whichever one you don't know.

Solve for impressions

Impressions = Ad spend ÷ CPM × 1,000

How many impressions a budget buys at a given CPM.

Solve for ad spend

Ad spend = Impressions ÷ 1,000 × CPM

What a target number of impressions will cost.

Solve for CPM

CPM = Ad spend ÷ Impressions × 1,000

The rate you paid per thousand impressions.

Dividing by 1,000 is the only step people trip on. A $12.50 CPM means each single impression costs $0.0125, which is why cost per impression is almost always quoted per thousand.

Worked examples

What the numbers look like in practice.

Each row holds two of the values fixed and solves for the third (shown in bold). Paste any of them into the calculator above to check the arithmetic.

ScenarioAd spendCPMImpressions
A $5,000 budget at a $12.50 CPM$5,000$12.50400,000
Buying 1,000,000 impressions at an $8 CPM$8,000$8.001,000,000
$2,400 spent for 150,000 impressions$2,400$16.00150,000
A $30 CPM campaign with a $1,500 budget$1,500$30.0050,000
Beyond the number

What CPM tells you, and what it doesn't.

Impressions are not reach

An impression is counted every time the ad is served, so one person seeing it four times is four impressions. Reach is the number of unique people. Divide impressions by reach to get frequency, which is the number you need when a cheap CPM is hiding an audience you have already saturated.

Not every platform bills by CPM

Meta, LinkedIn, TikTok, and display networks mostly charge per thousand impressions. Google Search charges per click, so the CPM you see there is derived after the fact from spend and impressions. The formula is the same either way, but only compare CPMs across platforms with that in mind.

A lower CPM is not a better ad

CPM measures what attention costs, not what it returns. Two campaigns with the same CPM can produce wildly different pipeline. Cometly's multi-touch attribution ties impressions and clicks to revenue, and AI Ads Manager uses that to tell you which spend to scale and which to cut.

Looking to bring CPA down rather than CPM? See how teams use Cometly to reduce CAC.

More free tools

Other calculators marketers reach for.

FAQ

CPM and impression questions, answered.

The formula, the conversions, and what the number can and can't tell you about a campaign.

Talk to sales
What is CPM in advertising?
CPM is cost per mille, meaning the cost of 1,000 ad impressions. It is the standard way ad platforms price and report the cost of showing an ad, regardless of whether anyone clicks. A $10 CPM means you pay $10 for every 1,000 times the ad is displayed.
How do you calculate impressions from CPM?
Divide your ad spend by the CPM and multiply by 1,000. Impressions = ad spend ÷ CPM × 1,000. For example, $5,000 of spend at a $12.50 CPM buys 5,000 ÷ 12.50 × 1,000 = 400,000 impressions.
What is the CPM formula?
CPM = ad spend ÷ impressions × 1,000. If you spent $2,400 to get 150,000 impressions, the CPM is 2,400 ÷ 150,000 × 1,000 = $16. The same identity rearranges to ad spend = impressions ÷ 1,000 × CPM and impressions = ad spend ÷ CPM × 1,000.
How much will a campaign cost at a given CPM?
Divide the number of impressions you want by 1,000, then multiply by the CPM. Buying 1,000,000 impressions at an $8 CPM costs 1,000,000 ÷ 1,000 × 8 = $8,000. Platforms that bill per click rather than per impression will not charge this exact amount, but the estimate still works for planning.
What is the difference between CPM and cost per impression?
Cost per impression is the price of a single impression, which is CPM divided by 1,000. A $12.50 CPM is a cost per impression of $0.0125. Because that number is a fraction of a cent, the industry quotes it per thousand instead.
How do I convert CPC to CPM?
Multiply the CPC by the click-through rate (as a decimal) and then by 1,000. CPM = CPC × CTR × 1,000. A $2.00 CPC at a 1% CTR is an effective $20 CPM. Going the other way, CPC = CPM ÷ (CTR × 1,000).
What is a good CPM?
It depends on the platform, the audience, the placement, the ad format, and the time of year. B2B audiences and professional networks such as LinkedIn generally cost more per thousand than broad consumer targeting, and CPMs rise in competitive seasons like Q4. The most useful benchmark is your own history on the same platform and audience. Judge the campaign by cost per acquisition, pipeline, and return on ad spend rather than by CPM alone.
Are impressions the same as reach?
No. Impressions count every time the ad is served, including repeat views by the same person. Reach counts unique people. Impressions divided by reach gives frequency, the average number of times each person saw the ad.
Does a lower CPM mean my ads are performing better?
Not necessarily. CPM only tells you what the impressions cost, not what they produced. A cheap CPM can come from a broad, low-intent audience that never converts, while a more expensive CPM aimed at the right buyers can return far more revenue. Attribution software that connects impressions and clicks to pipeline and revenue is how you tell the two apart.
Does this CPM impression calculator work for Meta, Google, LinkedIn, TikTok, and YouTube?
Yes. The relationship between spend, CPM, and impressions is the same on every platform and in every currency, so the calculator works for any of them. Just make sure spend and CPM are entered in the same currency.

Impressions are a cost.
Revenue is the result.

Cometly connects every ad impression and click to pipeline and revenue, so you can judge campaigns by what they return, not just what they cost.

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