CPM Calculator (Cost per Mille)

The three CPM formulas, worked through

Cost, impressions and CPM are locked together, so any two give you the third. The × 1,000 is the step people drop: cost ÷ impressions is the price of a single impression, usually a fraction of a cent, and CPM scales it to a thousand so it is readable. Each example below can be redone on a phone calculator.

1. Find CPM from cost and impressions

CPM = (cost ÷ impressions) × 1,000

A campaign spent $100 and was shown 25,000 times. $100 ÷ 25,000 = $0.004 per impression. $0.004 × 1,000 = $4.00 CPM. To check it, go backwards: $4.00 × 25,000 ÷ 1,000 = $100.

2. Find cost from CPM and impressions

Cost = CPM × impressions ÷ 1,000

A publisher quotes a $12.50 CPM for 120,000 impressions. $12.50 × 120,000 = 1,500,000, and 1,500,000 ÷ 1,000 = $1,500. This mode is most useful for fixed-price buys, where the CPM is agreed in advance.

3. Find impressions from a budget and CPM

Impressions = (budget ÷ CPM) × 1,000

You have $500 and expect a $5 CPM. $500 ÷ $5 = 100, and 100 × 1,000 = 100,000 impressions. On Google and Meta, ads are bought through an auction, so the price can change from day to day. Read this as what the budget buys at that price, not a delivery promise. For a full monthly plan that runs through to clicks and conversions, use the ad budget calculator.

CPM to cost per impression

CPM stands for cost per mille, which means cost per thousand, and Google's glossary calls it “Cost-per-thousand impressions (CPM)”. To get the cost per impression, divide the CPM by 1,000: a $4.00 CPM is $0.004, or four-tenths of a cent, each time the ad is shown. The last two columns use the impressions formula to show what $100 and $1,000 buy at each price.

At every CPM in the table, one impression costs five cents or less, so the price per 1,000 is the easier number to read and compare. To switch between cost per mille and cost per impression, move the decimal point three places.

What one impression actually buys

An impression is one showing of an ad. It is not a person: someone who scrolls past your ad three times is three impressions and one unit of reach. That is why a CPM tells you the price of attention, not how many people you paid to reach. The impressions vs reach explainer covers the difference in more depth.

Platforms also disagree on when an impression counts. Google's glossary describes CPM as “a way to bid where you pay per one thousand views (impressions) on the Google Display Network,” and Google also offers viewable CPM (vCPM), where, in Google's words, “you only pay when ads are measured as viewable by Active View.” Its help page on viewable CPM sets the bar: “50 percent of your ad shows on screen for one second or longer for display ads, and two seconds or longer for video ads.” A separate Google page notes that “vCPM bidding is unavailable for Search Network campaigns.” So a $4 vCPM and a $4 CPM are not the same price: with vCPM you don't pay for impressions that missed that bar.

Google's threshold matches the industry standard from the Media Rating Council. Its Viewable Ad Impression Guidelines (version 2.0, August 18, 2015) require at least 50% of an ad's pixels in view for at least one continuous second for display, and two continuous seconds for video. Very large display ads, 242,500 pixels or more (the area of a 970 × 250 banner), need only 30% of their pixels in view. The document says it was written for desktop browser ads, not mobile.

You will also see eCPM, or effective CPM. It is a general term rather than a way of buying: it takes the cost of any campaign, however it was billed, and restates it per 1,000 impressions so you can compare. If you pay per click and spent $60 on 20,000 impressions, your eCPM is $60 ÷ 20,000 × 1,000 = $3.00. We did not find a primary source that defines eCPM, so treat this as a working definition.

CPM, CTR and CPC are one equation

If you know your CPM and click-through rate, you already know your cost per click:

CPC = CPM ÷ (CTR × 10), with CTR in percent

It follows from the definitions. CPC is cost ÷ clicks. Cost is CPM × impressions ÷ 1,000, and clicks are impressions × CTR ÷ 100. The impressions cancel, leaving CPM ÷ (CTR × 10). With a $4.00 CPM and a 1% CTR, CPC = $4.00 ÷ 10 = $0.40. Double the CTR to 2% and the same CPM gives a $0.20 click. Doubling CTR does as much for your click cost as halving your CPM. The CPC vs CPM and CPM vs CTR guides go further, and if you have spend, impressions and clicks in hand, the CPC, CPM and CTR calculator returns all three at once. To work back from a target CTR to the clicks it needs, use the CTR calculator.

What is a good CPM? There is no honest single number

Meta and Google don't publish an average CPM that we could find when we checked on 2026-10-05. Third-party blogs do publish Meta CPM “averages”, but the ones we read disagreed with each other. They came from vendor datasets weighted toward e-commerce brands, or they didn't explain how the figure was calculated. We don't reprint them. A number built from someone else's audience, format and month tells you very little about yours.

CPM comes out of an auction. Meta's developer documentation describes “the Facebook ad auction”, where your bid strategy, bid amount and the probability of reaching your optimization goal are combined into “an effective bid”. Google says of viewable CPM bids that “the higher your max viewable CPM, the greater the chance that your ad will appear.” So the price you pay depends on who else is bidding for the same people and placements at the same time, which no published average can capture. The benchmark that holds up is your own. Run the last 30 days of one campaign through the calculator. Then compare it with the same campaign's previous 30 days, or with another campaign on the same platform, placement and objective.

A low CPM is not the goal

Ad tools, ours included, have a reason to blur this point. CPM is an easy number to improve without improving anything else: cheaper placements or a looser audience can lower the price per thousand while the people seeing the ad become less likely to buy. CPM is a price per showing, not a result. Take two hypothetical campaigns:

• Campaign A: $4 CPM, 0.5% CTR, 2% of clicks convert. CPC = $4 ÷ 5 = $0.80. Cost per customer = $0.80 ÷ 0.02 = $40.
• Campaign B: $12 CPM, 2% CTR, 5% of clicks convert. CPC = $12 ÷ 20 = $0.60. Cost per customer = $0.60 ÷ 0.05 = $12.

B pays three times as much per thousand impressions and gets customers at less than a third of the cost. The chain runs from CPM to click-through rate to conversion rate to cost per acquisition, and a cheap first step can't make up for weak ones after it. Judge campaigns on cost per acquisition or return on ad spend, and use CPM to explain why those moved. The CPA vs CPM comparison and the guide to budgets, pacing and pricing cover where each metric belongs.

Six common CPM mistakes

1. 01

   Dropping the × 1,000.

   $100 ÷ 25,000 is $0.004. That is the cost of one impression, not the CPM. If your answer has two or three zeros after the decimal point, you have stopped one step early.

2. 02

   Mixing date ranges or currencies.

   Cost from one export and impressions from another, covering different days, gives a CPM that never existed. Pull both numbers from the same report, for the same dates, in the same currency.

3. 03

   Comparing a billed CPM with a calculated one.

   A CPM bid is a ceiling (Google calls it the maximum you're willing to spend for 1,000 viewable impressions), and a quoted CPM is a price you agreed to. A CPM you calculate from a report is what you actually paid per 1,000 counted impressions. Compare them only when both use the same definition of an impression.

4. 04

   Treating a low CPM as a win.

   Cheap impressions shown to the wrong people cost more per customer, not less. Check CTR and cost per acquisition before you celebrate a falling CPM (see the example above).

5. 05

   Reading impressions as people.

   Impressions count showings. For people, use reach, and divide impressions by reach to get frequency.

6. 06

   Comparing CPMs across platforms that count differently.

   A served-impression CPM and a viewable-impression CPM are different prices for different things. The same applies across formats: a video view and a banner showing are not the same unit, even if both are called an impression.

CPM questions

Sources

Every quote below was last verified on 2026-10-05. The formulas and worked examples on this page are arithmetic and need no source.

• Google Ads Help

  Cost-per-thousand impressions (CPM): Definition

  “A way to bid where you pay per one thousand views (impressions) on the Google Display Network.”

  Google's glossary entry. No last-updated date is shown on the page. Last verified 2026-10-05.

• Google Ads Help

  Cost-per-thousand viewable impressions (viewable CPM)

  “An ad is counted as ‘viewable’ when 50 percent of your ad shows on screen for one second or longer for display ads, and two seconds or longer for video ads.”

  No last-updated date is shown on the page. Last verified 2026-10-05.

• Google Ads Help

  About bidding on impressions

  “vCPM bidding is unavailable for Search Network campaigns.”, “You don’t pay for any impressions that were not viewable.” and “The higher your max viewable CPM, the greater the chance that your ad will appear.” Its comparison table describes the vCPM bid as the “Maximum amount you're willing to spend for 1000 viewable impressions”.

  No last-updated date is shown on the page. Last verified 2026-10-05.

• Meta for Developers

  Bidding overview (Marketing API)

  “In the Facebook ad auction, Facebook evaluates your bid_strategy, bid_amount, and the probability of acquiring your optimization_goal to calculate an effective bid”

  Developer documentation for the Marketing API. No last-updated date is shown on the page. Last verified 2026-10-05.

• Media Rating Council

  Viewable Ad Impression Measurement Guidelines, Version 2.0 (August 18, 2015)

  Display: “Greater than or equal to 50% of the pixels in the advertisement were on an in-focus browser tab on the viewable space of the browser page” for “greater than or equal to one continuous second, post ad render.” Video: “2 continuous seconds.”

  Written for desktop browser ads. It is an industry standard, not a description of how any one platform bills. Last verified 2026-10-05.

• Meta Business Help Center

  CPM (Cost per 1,000 Impressions)

  Not quoted. Only the page title loaded for us, so we link it without quoting it.

  Meta's own definition page. Page date could not be confirmed. Last verified 2026-10-05.

What we could not confirm

• The body text and date of Meta's CPM help page. It would not load beyond its title, so we describe the formula in our own words.
• Any official average CPM from Meta or Google. We did not find one published by either company.
• Third-party CPM averages. The ones we checked disagreed with each other and either did not disclose their method or came from vendor datasets weighted toward e-commerce brands.
• When Google's help page was last updated. It says viewable CPM bidding “will be replacing CPM bidding”, but shows no date, so we can't say when or whether that change finished.
• A primary source for the term eCPM. The definition below is a general working definition.
• Which specific factors push Meta CPMs up or down. Meta's “About ad auctions” help page loaded only its title for us, so we describe the auction from Meta's developer documentation, which does not give CPM levels.