Marketing

CPM Calculator

Calculate CPM — the cost per thousand impressions — from ad spend and impressions delivered.

Enter ad spend and impressions for the same campaign and period.

Enter your values

Media spend for the campaign over the measurement period.

$

Impressions delivered for the same campaign and period.

impressions

Results

CPM

Enter ad spend and impressions.

Ad spend

The spend figure entered.

Impressions

The impressions entered.

Results are estimates based on the values entered and are provided for general planning.

Method

How to calculate CPM

The M in CPM is the Roman numeral for one thousand — mille — so CPM is the cost of a thousand impressions, not the cost of a single impression. Divide spend by impressions to get the cost of one impression, then multiply by 1,000 to express it in the standard unit the industry quotes.

Formula

CPM = Ad spend ÷ Impressions × 1,000

Assumptions

  • Ad spend and impressions come from the same campaign and reporting period.
  • Impressions is a positive whole number.
  • Impressions are counted as the platform defines and reports them.
  • Viewability standards differ between platforms and are not adjusted for here.

The division is calculated at full precision before display. Currency displays two decimals; impressions display as whole numbers.

How to interpret the result

CPM prices delivery, not outcomes. It tells you what it costs to put your ad in front of a thousand opportunities to see, and nothing about whether anyone clicked, remembered, or bought. Rising CPM in a stable campaign usually points to increased auction competition or a narrowing audience.

CPM vs CPC

CPM is the price of reaching a thousand people; CPC is the price of one of them acting. The link between them is click-through rate: at a fixed CPM, doubling click-through rate halves CPC.

Buying on a CPM basis puts delivery risk on you — you pay whether or not anyone clicks. Buying on a CPC basis shifts it to the platform.

CPM vs CPA

CPM sits at the very top of the funnel and CPA at the bottom. Between them lie click-through rate and conversion rate, and either can break the connection between a cheap CPM and an affordable CPA.

Awareness campaigns are usually judged on CPM and reach; direct-response campaigns on CPA. Using the wrong measure for the objective leads to the wrong optimisation.

Frequently asked questions

Cost per mille — mille being Latin for thousand. It is the cost of one thousand impressions, which is why the formula multiplies by 1,000.

No. Cost per impression is CPM divided by 1,000. A $4.00 CPM is $0.004 per impression. Describing CPM as cost per impression overstates the price by a factor of a thousand.

Divide ad spend by impressions delivered, then multiply the result by 1,000.

Impressions are counted events, so fractions are not meaningful, and dividing by zero impressions has no defined result.

Not on its own. Cheap impressions delivered to a poorly matched audience can produce no clicks or sales. Read CPM alongside click-through rate, CPC, and conversion outcomes.

Keep calculating

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CPC prices the same spend against clicks, CPA prices it against conversions, and ROAS connects it to the revenue generated.

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