---
title: "Cost per mille"
url: https://marketingsignals.com/glossary/cost-per-mille
type: Page
---

# Cost per mille

CPM explained: how to calculate cost per thousand impressions, how viewable CPM works in Google Ads, and when buying on CPM makes sense for a campaign.

PPC glossary

## Cost per mille (CPM)

Cost per mille (CPM) is the price an advertiser pays for 1,000 impressions of an ad, from the Latin mille, meaning thousand. It is calculated by dividing ad cost by impressions and multiplying by 1,000, and it is the usual way to buy and compare display, video and social advertising.

## How is CPM calculated?

Divide what the ads cost by the number of impressions, then multiply by 1,000. A campaign that costs £500 for 200,000 impressions has a CPM of £2.50.

Any campaign has a CPM, even one bought on cost per click, so it is a fair way to compare the cost of reach across YouTube, display and social platforms.

## What is viewable CPM?

On the Google Display Network, Google Ads uses viewable CPM (vCPM): you pay only when Active View measures an ad as viewable. Google has moved existing CPM bids to vCPM and suggests raising bids when switching, because viewable impressions are worth more.

- Display ads: at least 50% of the ad's area on screen for at least one second
- Large display ads of 242,500 pixels or more: at least 30% of the area for one second
- Video ads: at least 50% of the area on screen while playing for at least two seconds

## When should you buy on CPM?

When the goal is to be seen by a defined audience, such as launching a product or building awareness in a new region. It is the wrong measure when the goal is sales: a low CPM often means cheap placements few people pay attention to. Judge CPM campaigns on reach, frequency and what happens afterwards, such as growth in branded searches or a lift shown in an incrementality test.

## Example

A drinks brand runs two YouTube campaigns. One delivers 1 million impressions at a £3 CPM, the other 400,000 at £7.50, so both cost £3,000. The first looks better value, but if the second reaches a tighter audience and branded searches rise more in its test regions, it has done more of the job the budget was set for.

## Related terms

- [Cost per click (CPC)](https://marketingsignals.com/glossary/cost-per-click)
- [CPC vs CPM](https://marketingsignals.com/glossary/cpc-vs-cpm)
- [Demand Gen](https://marketingsignals.com/glossary/demand-gen)
- [Share of search](https://marketingsignals.com/glossary/share-of-search)
- [Incrementality testing](https://marketingsignals.com/glossary/incrementality-testing)

## Further reading

Our [Pay Per Click](https://marketingsignals.com/service/pay-per-click) service puts this into practice for brands in the UK and US.

## Sources

- [Cost-per-thousand impressions (CPM): Definition, Google Ads Help](https://support.google.com/google-ads/answer/6310)
- [Cost-per-thousand viewable impressions (viewable CPM), Google Ads Help](https://support.google.com/google-ads/answer/6026409)
- [Understanding viewability and Active View reporting metrics, Google Ads Help](https://support.google.com/google-ads/answer/7029393)

## Ready To Make Your Ad Spend Work Harder?