CPM
CPM (cost per mille, or cost per 1,000 impressions) is the average amount you paid for every 1,000 times your ad was on screen. Meta calculates it as amount spent divided by impressions, multiplied by 1,000. It tells you what reaching eyes cost in a given auction, not whether those people clicked or bought, so it is read next to cost per result, never instead of it.
How does Meta define CPM?
Meta's CPM metric page calls it "The average cost for 1,000 impressions" and says it is "a common metric used by the online advertising industry to gauge the cost-effectiveness of an ad campaign". The formula, with Meta's own example:
CPM measures the amount spent on an ad campaign, divided by impressions, multiplied by 1,000. For example, if you spent $50 and got 10,000 impressions, your CPM would be $5.
What counts as an impression?
Meta's Impressions page defines one as "the number of times an instance of an ad is on screen for the first time". Three details change how you read CPM:
| Situation | How Meta counts it |
|---|---|
| Someone scrolls past, then back up to the same ad | 1 impression |
| The ad is on screen for someone 2 different times in a day | 2 impressions |
| A video ad that never starts playing | Still an impression: "a video is not required to start playing" |
Meta also says impressions "aren't counted if they come from invalid traffic we detect such as from non-human sources, like a bot."
Is CPM what Meta charges you?
Often it is close. Meta's How Meta charges for ads says: "Usually, you're charged based on the number of impressions your ad receives unless specified otherwise during ad creation." The same page warns that "Ads Manager displays the total number of clicks and impressions your ad receives, while your receipt shows the number of clicks and impressions you're charged for. These numbers may differ."
What makes CPM go up or down?
The auction. Meta's About ad auctions says the winner "is the ad with the highest total value", a combination of your bid, "estimated action rates" and "ad quality". The line that matters for creative:
Together, estimated action rates and ad quality measure ad relevance. Because these are components of the auction, an ad that's more relevant to a person could win an auction against ads with higher bids.
None of the Meta pages cited here gives a benchmark for a "good" CPM. Any figure you see quoted as normal comes from somewhere else.
Is CPM or cost per 1,000 people reached better?
They answer different questions. Meta's Cost per 1,000 Meta Accounts reached page says "reach can be a more insightful metric than impressions, because it gives you a measure of how many Meta Accounts were exposed to your message". CPM counts every view; cost per 1,000 reached counts each person once. The gap between them is your frequency.
What it means for your ads
- Judge an ad on cost per result. A low CPM on an ad nobody acts on is a cheap way to buy nothing. A high CPM on an ad that converts can be fine.
- Compare like with like. Change the audience or placements and your ad enters different auctions, so the CPM that follows says little about the creative.
- Treat relevance as part of the price. Meta's own auction page says a more relevant ad can beat a higher bid, so a less relevant one can cost more to show.
Common mistakes
- Optimizing for CPM itself. It rewards whatever is cheapest to show, not what sells.
- Comparing your CPM to someone else's. None of the Meta pages cited here gives a benchmark, and their audience, placement and objective are not yours.
Sources
- CPM (cost per 1,000 impressions) — Meta Business Help Center metric glossary: the definition, how it is used and the formula with its example (rendered in a browser, accessed 2026-10-16)
- Impressions — Meta Business Help Center metric glossary: how an impression is counted, video, and invalid traffic (rendered in a browser, accessed 2026-10-16)
- How Meta charges for ads — Meta Business Help Center: charging on impressions, and Ads Manager versus receipt counts (rendered in a browser, accessed 2026-10-16)
- About ad auctions — Meta Business Help Center: total value, its three factors and ad relevance (rendered in a browser, accessed 2026-10-16)
- Cost per 1,000 Meta Accounts reached — Meta Business Help Center metric glossary: reach versus impressions (rendered in a browser, accessed 2026-10-16)
Meta's help pages are client-rendered and show no date; they were read in a real browser on 16 October 2026. Meta revises them without notice, so check the source before acting on any of it.
Terrads makes a batch of new image and video ads in one go, so when cost per result climbs you have fresh creative to test, not just a bid to raise.