What is CPM? Cost per thousand impressions explained
CPM, or cost per mille, is what you pay for one thousand ad impressions. Here is what CPM means, how to calculate it and convert it to CPC, a worked AED example and how to judge whether a CPM is good value.
CPM, or cost per mille, is what you pay for one thousand ad impressions. Mille is Latin for thousand. It is a common pricing model for social, video and display ads, and the standard way to compare the cost of reach across Meta, TikTok, Snapchat, YouTube and display networks. A lower CPM buys more impressions for the same budget.
How do you calculate CPM?
| Metric | Formula |
|---|---|
| CPM | Ad spend ÷ impressions × 1,000 |
| Impressions a budget buys | Budget ÷ CPM × 1,000 |
| CPM from CPC | CPC × CTR × 1,000 |
Google's CPM help page describes CPM bidding as "a way to bid where you pay per one thousand views (impressions)" on the Google Display Network, and notes that existing CPM bids are converted to viewable CPM (vCPM), which charges only when ads can be seen.
CPM example
Illustrative figures for a UAE retailer planning a Ramadan awareness push:
- Budget: AED 40,000. Expected CPM: AED 16.
- Impressions: AED 40,000 ÷ AED 16 × 1,000 = 2.5 million.
- If CPM rises to AED 25 in peak weeks, the same budget buys 1.6 million impressions, 36% fewer.
To hold 2.5 million impressions at AED 25, the budget would need to rise to AED 62,500.
What is a good CPM?
There is no single good CPM. It varies by platform, country, audience, ad format, season and how crowded the auction is, and peak periods such as Ramadan, White Friday and year-end can cost more. Compare CPM with your own history for the same audience and placement, and judge it together with CTR and conversion rate: a cheap impression nobody acts on is not good value.
Related terms
- Reach and ad frequency: impressions equal reach multiplied by frequency.
- CPC: cost per click, the next step down the funnel.
- Creative fatigue: high frequency on one ad often lowers CTR and raises cost per result.
How Grower helps
Grower's channels leaderboard shows cost and impressions next to ROAS, CPA and CTR for every connected channel, including Snapchat, TikTok, Meta and YouTube. The calendar puts campaigns from every channel on one timeline by month, week or day.
Frequently asked questions
What does CPM stand for?
CPM stands for cost per mille, from the Latin word for thousand, and is sometimes written as cost per thousand impressions. It is the price of one thousand ad impressions. Google Ads also uses viewable CPM (vCPM), where you pay only for impressions that could be seen. Use CPM to compare the cost of reach across platforms.
Is CPM or CPC better?
Neither is better on its own. CPM buying suits awareness goals, where you want as many people as possible to see the ad. CPC buying suits traffic goals, where you only want to pay for visits. Compare them on a common basis: effective CPM equals CPC × CTR × 1,000, and effective CPC equals CPM ÷ (CTR × 1,000).
Why is my CPM increasing?
Usually because more advertisers want the same audience: peak seasons, narrow targeting or new competitors bidding on your segment. Creative fatigue can also push costs up as engagement drops. Broaden audiences, refresh creative, test new placements and compare with the same period last year before you change budgets or decide a channel has become too expensive.
Plan your next campaign budget with the free marketing budget calculator, and read our White Friday playbook for planning around peak-week CPMs.