What Is CPM? Cost Per Mille Explained, Plus Viewable CPM for Advertisers

Google's own definition is that CPM is a way to bid where you pay per one thousand views, or impressions, on the Google Display Network. This page is about CPM from the advertiser's side. If you're a creator wondering what YouTube pays you, that's a different question, and it's covered in this guide to YouTube CPM for creators.

The CPM formula, with a worked example

CPM = total ad cost divided by impressions, multiplied by 1,000

Turn it round and you can work out what a set number of impressions will cost. Google's help page uses a max viewable CPM bid of $1.20 as its example. At that bid, you're offering up to $1.20 for every 1,000 viewable impressions, so 10,000 viewable impressions would cost no more than $12. (That's simple arithmetic on Google's example bid, as of October 2026, not a price you should expect to pay.)

Because you're paying for views rather than clicks, CPM tells you nothing about whether anyone did anything after seeing the ad. That's the job of other metrics like click-through rate and cost per conversion.

CPM vs viewable CPM on Google

Google says existing CPM bids are converted to viewable CPM automatically. It still recommends updating your bids yourself, because viewable impressions are potentially more valuable than the old kind.

With vCPM you bid on 1,000 viewable impressions and only pay for impressions measured as viewable. Google counts a Display ad impression as viewable when 50% of the ad shows on screen for 1 second or longer. For video ads, it's viewable when the ad plays continuously for 2 seconds or longer.

Bid type	You pay for	Google's stated best fit
CPC	Each click	Traffic and clicks
CPM (now vCPM)	1,000 impressions	Awareness on Display
vCPM	1,000 viewable impressions only	You want ads seen, not necessarily clicked
Maximize conversions	Conversions, with automated bidding	Sales or sign-ups

The catch: your vCPM bid probably needs to be higher

This is the bit that surprises people moving from an old CPM campaign. Google says that to keep costs and traffic at the same level as a CPM campaign, your vCPM bid might need to be higher than a standard CPM bid. The reason is that you no longer pay for impressions that weren't viewable, so each impression you do pay for is worth more.

Google goes further and says a higher vCPM bid than CPM bid is usually more effective for winning these more valuable impressions, and that you should experiment. So if your volume drops after the switch, the bid is the first thing to look at, not the ads.

When CPM bidding makes sense, and when it doesn't

Google's advice is clear. Bid on viewable impressions when you care more about your ads being seen than about clicks. If your main goal is online sales or website visits, Google says Maximize clicks or Maximize conversions may be a better option.

There are a few practical limits too. vCPM bidding isn't available for Search Network campaigns. You select it by choosing CPM bidding for a 'Display Network only' campaign. And if you create a campaign with vCPM and then add ads that aren't compatible with it, those ads won't run.

How CPM ads compete with click-based ads

On the Display Network, an advertiser paying per click and one paying per thousand views can both want the same spot. Google compares them on how much each is effectively willing to pay per impression. For a CPC ad, Google estimates how many clicks it might get per 1,000 impressions, which turns a click bid into something it can compare with a vCPM bid.

For comparison, with CPC bidding you pay for each click and set a max CPC, which is the most you'll typically pay. Google notes you're often charged less than that, and the amount you're charged is your actual CPC.

Setting your bids and reading the reports

You can set a max viewable CPM at ad group level, which applies the same bid to every keyword and placement in that group. Google's example bid is $1.20. You can also set bids at placement level for sites that perform well for you. One detail worth knowing: text ads that win a placement with a vCPM bid are given the entire ad space.

To see how you're doing, add the viewability columns. In Google Ads go to Views, then Display or Video campaigns, then Columns and Modify columns. Avg. viewable CPM is your average cost per 1,000 viewable impressions, and Measurable rate is the percentage of impressions that could be measured.

If you bid for results rather than views, read about CPA and Target CPA.

Setting up a vCPM campaign, step by step

1. Pick the goal first: do you want your ads seen, or clicked and converted?
2. If it's seen, choose a Display Network only campaign and CPM bidding, which gives you vCPM.
3. Set a max viewable CPM at ad group level to start.
4. Add placement bids for the sites that perform for you.
5. Add the Avg. viewable CPM and Measurable rate columns to your reports.
6. If volume drops compared with an old CPM campaign, raise the bid and test again.

Impressions only matter if people click, which is what click-through rate measures.

Should you pay by CPM?

CPM suits awareness. If you want people to see your brand, a launch or an offer, paying per thousand viewable impressions is a fair way to buy that. But if what you need is sales or leads, paying for impressions can burn through your budget without a single result, and Google itself points you to Maximize clicks or Maximize conversions for that job.

And remember that an impression isn't the same as a person. If you're comparing reach across platforms, this explainer on accounts reached vs impressions shows why the two numbers differ. Whatever you bid on, check your account for the Google Ads budget leaks small businesses miss before you spend more.

Frequently asked questions

What does CPM stand for?

CPM stands for cost per mille, or cost per thousand impressions. It's what an advertiser pays each time an ad is shown 1,000 times.

How do you calculate CPM?

Divide your total ad cost by the number of impressions, then multiply by 1,000. Google reports viewable CPM as Avg. viewable CPM, the average cost per 1,000 viewable impressions.

What is viewable CPM?

With viewable CPM you only pay for impressions measured as viewable. Google counts a Display ad as viewable when 50% of the ad shows on screen for 1 second or longer, and a video ad when it plays for 2 seconds or longer.

Can I use CPM bidding on Google Search?

No. Google says vCPM bidding is unavailable for Search Network campaigns. You choose CPM bidding for a Display Network only campaign.