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CPM calculator

Enter any two of cost, impressions and CPM to get the third. Add clicks and conversions to see your cost per click, click-through rate and cost per acquisition, all from the same numbers.

What do you want to work out?

What you spent, or plan to spend, on the ads.

How many times the ads were shown.

Optional: add results to see click and conversion costs.

Sales, sign-ups or whatever action you count.

CPM (cost per 1,000 impressions)
$2.50
$500.00 for 200,000 impressions
Cost
$500.00
Impressions
200,000
CPM
$2.50
Cost per impression
$0.0025
  • Nothing is uploaded
  • Free, no sign-up
  • Works on phone and desktop

How to calculate CPM

  1. 1

    Choose what to work out: the CPM, the cost of a campaign, or the impressions a budget buys.

  2. 2

    Enter the other two numbers, such as what you spent and how many impressions the ads got.

  3. 3

    Add clicks and conversions from your ad platform's report if you have them.

  4. 4

    Read the CPM, CTR, CPC and CPA together, then copy them or copy a link to the numbers.

Features

  • Any two, get the third

    Work out CPM from a report, the cost of a planned buy, or how many impressions a budget gets you.

  • CPC and CPA

    Add clicks and conversions to see what each click and each customer really cost.

  • Click-through and conversion rates

    See CTR and conversion rate next to the costs, so you can tell which number is holding a campaign back.

  • Plans and reports

    Plan a budget from a quoted CPM, or check what a finished campaign cost per thousand. Five currencies.

The formulas

  • CPM = cost ÷ impressions × 1,000
  • Cost = CPM × impressions ÷ 1,000
  • Impressions = cost ÷ CPM × 1,000
  • CTR (click-through rate) = clicks ÷ impressions × 100
  • CPC (cost per click) = cost ÷ clicks
  • Conversion rate = conversions ÷ clicks × 100
  • CPA (cost per acquisition) = cost ÷ conversions

A campaign, start to finish

Say a campaign spent $1,200 and the report shows 400,000 impressions, 2,000 clicks and 50 sales.

MetricSumResult
CPM$1,200 ÷ 400,000 × 1,000$3
CTR2,000 ÷ 400,0000.5%
CPC$1,200 ÷ 2,000$0.60
Conversion rate50 ÷ 2,0002.5%
CPA$1,200 ÷ 50$24

How the numbers connect

The metrics are links in one chain. The cost per click is the CPM spread over the clicks each thousand impressions bring: at a $3 CPM and a 0.5% CTR, 1,000 impressions bring 5 clicks, so each costs $0.60. The cost per sale is the CPC spread over the share of clicks that buy: $0.60 ÷ 2.5% = $24.

That means there are three levers, not one. Halving the CPM halves the CPA, but so does doubling the click-through rate with a better ad, or doubling the conversion rate with a better landing page. When a CPA is too high, the breakdown shows which link is weakest.

Planning a buy

  • Impressions for a budget: $2,000 at an $8 CPM buys about 250,000 impressions.
  • Budget for a reach goal: 150,000 impressions at a $12 CPM cost $1,800.
  • Publisher earnings: a site that earned $84 from 30,000 ad impressions had an eCPM of $2.80.

The CPMs above are just round numbers for the arithmetic, not typical prices. Real CPMs vary widely: by platform and ad format, by how narrowly you target, by country, and through the year as more advertisers compete for the same people. Use your own past campaigns and your platform's estimates as the yardstick.

Check what's being counted

The sums are simple; the inputs are where comparisons go wrong. Platforms don't all count an impression the same way: some count an ad as soon as it is served, others only once it is viewable on screen, and video platforms may count views separately. Clicks can mean link clicks or any click on the ad, and a conversion is whatever you told the platform to count, within its attribution window. Before comparing two campaigns or two platforms, make sure the cost, impressions, clicks and conversions cover the same dates and the same definitions.

Is the campaign worth it?

A CPA only means something next to what a customer is worth. If each sale earns a $40 contribution after the cost of the product, a $24 CPA leaves $16 per sale; a CPA above $40 loses money on every order. Work out your contribution per sale with the break-even calculator or the margin calculator, and compare the campaign's total return with the ROI calculator.

Frequently asked questions

How do you calculate CPM?

Divide the cost by the number of impressions and multiply by 1,000. $500 for 200,000 impressions is a $2.50 CPM.

What does CPM stand for?

Cost per mille, where mille is Latin for thousand. It is the price of 1,000 ad impressions, whether you buy on a CPM basis or on clicks and work the CPM out afterwards.

What is a good CPM?

There's no single good number. CPMs vary widely by platform, ad format, audience, country and time of year, and a cheap CPM is no bargain if nobody clicks or buys. Compare a campaign with your own earlier ones and with your platform's estimates, and judge it by CPC and CPA as well.

What is the difference between CPM, CPC and CPA?

They divide the same cost by different things. CPM divides it by impressions (per 1,000), CPC by clicks, and CPA by conversions such as sales or sign-ups. A campaign can have a low CPM and still a high CPA if few people act on the ad.

How do I calculate CTR?

Divide clicks by impressions and multiply by 100. 1,200 clicks from 200,000 impressions is a 0.6% click-through rate.

What is eCPM?

Effective CPM: what a publisher earns, or an advertiser pays, per 1,000 impressions, whatever the ads were actually sold on. The sum is the same, so enter earnings as the cost to use this calculator for it. Publishers often call the page-level version RPM.

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