Cost Per Mille (CPM)
Also known as: CPM, Cost Per Mille, Cost Per Thousand Impressions, vCPM
CPM, short for cost per mille, is what an advertiser pays for one thousand ad impressions. Mille is Latin for thousand. The formula is total cost divided by impressions, times 1,000, so $50 spent on 10,000 impressions is a $5 CPM. It is the standard pricing unit for awareness and reach campaigns.
Key Takeaways
- CPM is the cost of one thousand impressions, whether or not anyone clicks.
- Formula: CPM = (total cost / impressions) x 1,000.
- It works both as a metric for comparing reach costs and as a way to bid and pay.
- In Google Ads, viewable CPM (vCPM) bidding charges only for impressions where the ad could be seen.
- CPM, CPC, and click-through rate are linked: CPM equals CPC x CTR x 1,000.
How It Works
CPM has two jobs. As a metric, it puts the cost of reach on a common scale, so you can compare a video placement, a social campaign, and a display network buy even when they are priced differently. As a pricing model, it means you pay for impressions rather than clicks. Google Ads describes CPM bidding as a way to bid where you pay per one thousand views on the Google Display Network, and notes that viewable CPM (vCPM) bidding ensures you only pay when your ads can be seen (Google Ads Help).
The math connects CPM to click pricing. Cost per thousand impressions equals cost per click multiplied by click-through rate, times 1,000. If your CPC is $1.00 and your CTR is 0.5 percent, your effective CPM is $5. Running the formula in both directions tells you whether paying per impression or per click is the better deal for a given placement and creative.
Use CPM pricing when being seen is the goal: launches, brand awareness, and building audiences you will retarget later. Judge it on reach, frequency, and lift in branded searches or direct visits, not only on last-click sales. If the goal is a lead or a sale, click or conversion-based bidding is usually the better fit, which I cover in the PPC hub.
Why It Matters
CPM lets you compare the cost of reach across placements and platforms on an even footing. For top-of-funnel branding, buying impressions efficiently can be smarter than paying per click, especially when the aim is exposure to a wide audience.
Example
A new coffee shop spends $300 on a local video campaign and gets 60,000 impressions, a $5 CPM. A second placement offers clicks at $1.20 with an expected click-through rate of 0.3 percent, which works out to a $3.60 effective CPM. Because the goal is awareness in a few neighborhoods, the owner compares reach and frequency in each before choosing, not just the price.
Common Mistake
Judging a CPM awareness campaign by direct clicks or last-click conversions. Reach campaigns build recognition that pays off later, so measuring them with a bottom-funnel yardstick makes them look like failures and gets them cut prematurely.
Frequently Asked Questions
What does CPM mean in advertising?
CPM means cost per mille, the price of one thousand ad impressions. Advertisers use it to compare the cost of reaching people across platforms, and many awareness campaigns are bought on a CPM basis, paying for views rather than clicks.
What does cost per mille mean?
Mille is Latin for thousand, so cost per mille means cost per thousand. In advertising it is the cost of one thousand impressions. It is the same thing as cost per thousand impressions, and both are abbreviated CPM.
How do you calculate CPM?
Divide total ad cost by total impressions, then multiply by 1,000. For example, $200 spent on 40,000 impressions is $200 / 40,000 x 1,000 = $5 CPM. You can also work out CPM from CPC: CPC x click-through rate x 1,000.
What is a good CPM?
It depends on the platform, placement, audience, location, and season, so a universal number misleads. A good CPM is one where the people reached are the right people and the campaign moves a goal you can measure, like branded search or site visits.
What is viewable CPM?
Viewable CPM, or vCPM, is a Google Ads bidding option for Display where you pay only for impressions in which your ad could actually be seen. Google says existing CPM bids are converted to vCPM automatically.
Should I use CPM or CPC?
Use CPM when the goal is reach and awareness and you want as many of the right people as possible to see the ad. Use CPC when you want visits, leads, or sales and only want to pay when someone engages. Many accounts use both at different funnel stages.