CPM calculator: cost per impression calculator with the CPM formula, CTR formula and CPC

How do you calculate CPM?

Divide your ad spend by the number of impressions, then multiply by 1,000. A $5,000 campaign that delivered 400,000 impressions has a CPM of $12.50. The multiplication by a thousand is the whole point of the metric: raw cost per impression is a number with four decimal places that nobody can hold in their head, so the industry quotes it per thousand instead. Mille is Latin for thousand, which is where the M comes from.

Run the formula backwards to price a campaign before you buy it. Multiply the CPM you expect by the impressions you want and divide by 1,000. If a publisher quotes $22 CPM and you want 750,000 impressions, that is $16,500. This is the arithmetic behind almost every media plan, and it is also where reach and impressions get confused. Impressions count times served; reach counts people. A 400,000 impression campaign at a frequency of 4 reached 100,000 people, and the CPM says nothing about which of those two numbers you were paying for.

How do you calculate CTR?

Divide clicks by impressions and multiply by 100 to get a percentage. 4,800 clicks on 400,000 impressions is a 1.2 percent click-through rate. Use the same date range and the same campaign scope for both numbers, because a CTR built from clicks in one window and impressions in another is not measuring anything.

On Meta, decide which click you mean before you calculate. The platform reports clicks (all), which includes likes, comments, shares and taps on your page name, and link clicks, which counts only taps that opened your destination. Clicks (all) can be double link clicks on a post with good engagement, so a CTR built on it looks excellent while sending nobody to the site. Use link clicks for anything you plan to compare against a landing page or a cost per click.

How do you calculate CPC from CPM and CTR?

Divide CPM by ten times the CTR percentage. A $12.50 CPM at a 1.2 percent click-through rate gives $12.50 divided by 12, which is $1.04 per click. The ten is there because CPM is priced per thousand impressions while CTR is expressed as a percentage, and the two scales differ by a factor of ten.

This identity is more useful than it looks, because it separates the two things that can make a click more expensive. If CPC rose and CPM is flat, your creative is earning fewer clicks per impression and the fix is creative. If CPC rose and CTR is flat, the auction got more expensive and the fix is bidding, targeting, or accepting a seasonal price. Most reporting shows all three metrics without ever saying which one moved first, so buyers spend weeks rewriting ad copy to solve a Q4 auction problem.

The second row of the table above makes the same point in reverse. A $12.50 CPM at 0.5 percent CTR and a $30 CPM at 1.2 percent CTR both buy exactly 400 clicks per $1,000. Cheap impressions are not cheap traffic.

What is a good CPM?

There is no cross-industry good CPM, and any single figure quoted as one should be treated with suspicion. CPM is the clearing price of an auction for a specific audience, in a specific placement, at a specific moment. A B2B campaign targeting finance directors on LinkedIn and a broad awareness campaign on TikTok are not buying the same thing, so comparing their CPMs is like comparing the price of a plane ticket to the price of a bus fare.

Three things move CPM more than anything you control in the ad account: how narrow your targeting is, how many other advertisers want the same people, and what time of year it is. Retail CPMs climb steeply through Q4 for the obvious reason. Narrow audiences cost more per thousand because there is less inventory to bid on. None of that makes a high CPM bad, because a $40 CPM reaching qualified buyers can produce a lower cost per acquisition than a $6 CPM reaching everyone.

The only benchmark worth holding yourself to is your own account, on the same audience, over time, alongside CTR and cost per acquisition. Judge CPM against last month and against what it produced, never against a number from a blog post that does not say which platform, country, audience or quarter it came from. If you need a downstream figure to judge it by, the customer acquisition cost calculator works out what a customer actually costs once every channel is counted.

Is CPM better than CPC?

They are billing models, not performance metrics, and the better one depends on what you are confident about. On CPM you pay for delivery and carry the risk that nobody clicks. On CPC you pay only for clicks and the platform carries that risk, which it prices into the bid. Neither is cheaper by nature, because both are settled in the same auction against the same competitors.

Buy on CPM when you want reach and your creative reliably beats the average click-through rate, since every click above average is effectively free. Buy on CPC when you are testing new creative, entering an unfamiliar audience, or cannot predict engagement, because a floor on cost per visit is worth paying for. On most modern platforms this choice is increasingly made for you: Google Search does not offer CPM bidding at all, and Meta and TikTok default to objective-based bidding where you set a cost target and the system chooses the unit.

The comparison that actually matters is further down the funnel. Cost per acquisition and return on ad spend decide whether a campaign made money, and a campaign can win on CPM, win on CPC and still lose on both. The full argument for judging channels on money rather than delivery metrics is in blended ROAS versus platform ROAS, and the choice between the three buying models is laid out in the best ad bidding model for each campaign goal.

What is the difference between CPM and vCPM?

CPM charges for impressions served. Viewable CPM, or vCPM, charges only for impressions measured as viewable, which Google defines through Active View as at least 50 percent of the ad on screen for at least 1 second for display, or 2 seconds for video. Large display units of 242,500 pixels or more need only 30 percent on screen for 1 second. An ad served below the fold that nobody scrolls to is an impression but not a viewable impression.

The practical consequence is that vCPM is always the higher number for the same campaign, because it divides the same spend by a smaller denominator. A campaign at a $12.50 CPM with 60 percent viewability has a viewable CPM near $20.83. That is not a price increase, it is the same money measured against the impressions that had a chance of working. Comparing a served CPM on one network against a viewable CPM on another is one of the most common ways a media comparison ends up backwards.

Why is my CPM different in Google Ads and Meta?

Partly because the auctions are genuinely different, and partly because the two platforms are not counting the same event. Meta counts an impression the first time the ad enters the screen. Google counts a display impression when the ad is served to the page, whether or not it ever comes into view, and reports viewability separately through Active View. Same word, two denominators, so the CPMs are not directly comparable even before audience and inventory differences.

This is the smaller version of a problem that gets much worse further down the funnel. Delivery metrics like spend, impressions, clicks, CPM, CPC and CTR are measured similarly enough across networks that comparing them is broadly fair once you know the counting rules. Attributed metrics like conversions, conversion value and platform ROAS are produced by three different attribution rulebooks with different windows, so a side-by-side table of those ranks networks by how generous their attribution is rather than by how well they sold anything.

MixedMetrics pulls spend, impressions, clicks and the derived CPM, CPC and CTR from Google Ads, Meta and TikTok onto one board on a shared date range through read-only connectors, and labels platform-reported conversions as platform-reported so nobody sums them. If you want the campaign-level view of the same data, the ad performance dashboard and the PPC dashboard both carry the CPM, CPC and CTR table per campaign.