Cost per mille (CPM) is the price you pay for 1,000 ad impressions. "Mille" is Latin for thousand, so CPM is also called cost per thousand. On Facebook and Instagram, it shows how expensive it is to reach your audience, before anyone clicks.
How to calculate CPM
CPM = (ad spend ÷ impressions) × 1,000
If you spend $500 and your ads get 62,500 impressions, your CPM is $8. Ads Manager calculates it for you in the CPM (cost per 1,000 impressions) column, which Meta defines as "the amount spent on an ad campaign, divided by impressions, multiplied by 1,000".
CPM links to your other cost metrics through click-through rate (CTR), written as a decimal (1% is 0.01):
CPC = CPM ÷ (CTR × 1,000)
At an $8 CPM and a 1% CTR, 1,000 impressions bring 10 clicks, so each click costs $0.80. Use the same kind of click on both sides: link CTR gives cost per link click. That is why a rising CPM doesn't always hurt: a better ad with a higher CTR can keep your cost per click (CPC) flat.
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Try for Free ($0 Trial)CPM, CPC and cost per result
| Metric | You divide spend by | It tells you |
|---|---|---|
| CPM | Impressions, times 1,000 | How costly it is to be seen |
| CPC | Clicks | How costly it is to get a visit |
| Cost per result | The results your campaign optimizes for | How costly each purchase, lead or other goal is |
CPM is the first cost in the chain: what it takes to be seen. CPC and cost per result show what that exposure turns into.
What drives CPM up on Meta
Meta sells ad space in an auction. Your CPM depends on how many other advertisers want the same people at the same time, and on how Meta rates your ad. Common causes of a higher CPM:
- Competition. CPMs usually rise in November and December, when retail advertisers bid for the same shoppers.
- Audience. A small or popular audience has fewer impressions to go around, so each one costs more.
- Placement. Prices differ between Feeds, Stories, Reels and other placements.
- Optimization goal. Campaigns optimizing for purchases often pay more per impression than reach campaigns, because Meta shows them to people more likely to buy.
- Ad quality. Ads that people hide or ignore lose ground in the auction. Costs also climb as an ad wears out on people who have seen it too often, which is ad fatigue in Meta ads.
How to read CPM
Judge CPM next to what it buys. A $20 CPM that brings purchases at your target cost beats a $6 CPM that brings none. Check three things:
- Compare CPM within the same placement, audience type and season, not across them.
- Watch the trend. A steady climb over a few weeks, with frequency rising too, often means the audience is tiring of the ad.
- Read it with CTR and cost per result before changing anything.
Example. A store's prospecting campaign runs at an $11 CPM in October. In late November its CPM reaches $17, while CTR holds at 1.4% and cost per purchase rises 20%. The creative is fine. The auction got busier for Black Friday, so the team keeps its best ads running and moves budget to them.
In Madgicx. AI Marketer audits your Meta ad account and points out where rising costs eat into results. Creative Insights flags creative fatigue, a common reason CPM and cost per result climb together, so you know when to refresh an ad.
FAQ
What is a good CPM for Facebook ads?
There is no single good CPM. It varies by country, audience, placement, season and goal. Compare your CPM with your own past results for the same kind of campaign, and judge it by the cost per result it leads to.
Why is my CPM so high?
The usual reasons are a narrow audience, a busy season, a purchase optimization goal, or an ad that people engage with less over time. Check frequency and CTR first: if both moved, the ad is likely the cause.
Is CPM the same as cost per impression?
Nearly. CPM is the cost of 1,000 impressions. Divide it by 1,000 to get the cost of a single impression, which is usually a fraction of a cent.
Does a lower CPM mean better ads?
Not on its own. A low CPM can come from cheap placements or broad audiences that rarely buy. Lower CPM helps only when CTR and conversions hold up.
What does CPM stand for?
CPM stands for cost per mille, from the Latin word for thousand. It is the cost of 1,000 impressions.
Related
- Related terms: Impressions, Reach, Cost per click (CPC), Frequency
- In depth: Facebook CPM: what it costs and how to lower it
Sources
- CPM (Cost per 1,000 Impressions), Meta Business Help Center
- About ad auctions, Meta Business Help Center
