What is CPM?
CPM (Cost Per Mille) is an advertising pricing model where advertisers pay a set rate for every 1,000 times their ad is displayed. It's widely used for brand awareness campaigns.
CPM stands for Cost Per Mille — from the Latin mille, meaning thousand. It's an advertising pricing model in which the advertiser pays a fixed rate for every 1,000 times their ad is shown (impressions), regardless of whether anyone clicks.
$$\text{CPM} = \frac{\text{Total Ad Spend}}{\text{Total Impressions}} \times 1{,}000$$
For example, if you pay $50 to have your ad shown 25,000 times, your CPM is $2.
CPM is one of the oldest and most widely used pricing models in advertising, used across display networks, social media platforms, streaming video, and traditional media like television and print.
CPM vs. CPC vs. CPA
| Model | What You Pay For | Best For |
|---|---|---|
| CPM | Every 1,000 impressions | Brand awareness and reach |
| CPC (Cost Per Click) | Each click | Driving website traffic |
| CPA (Cost Per Acquisition) | Each conversion | Direct-response performance campaigns |
CPM optimizes for reach — how many people see your ad. CPC optimizes for engagement. CPA optimizes for outcomes.
When to Use CPM
CPM is best for campaigns focused on:
- Brand awareness — Getting your name in front of as many relevant people as possible
- Product launches — Broad exposure to introduce something new
- Retargeting — Re-engaging people who've already visited your site (keeping your brand visible)
- Video advertising — Pre-roll and in-stream video ads are typically priced on CPM
If your goal is clicks or conversions, CPM alone doesn't tell you how efficiently you're achieving those outcomes. You'd also want to track your effective click-through rate and conversion rate.
What Affects CPM Rates?
- Platform — Rates vary widely: LinkedIn CPMs can be $30–$100+; Facebook/Instagram averages $5–$15; display networks $1–$5
- Audience targeting — More specific audiences (by income, job title, behavior) cost more
- Ad format — Video ads typically command higher CPMs than static images
- Season — CPMs rise sharply in Q4 as advertisers compete for holiday shoppers
- Ad quality — Platforms reward relevant, engaging ads with better placement and lower effective costs
Effective CPM (eCPM)
When a campaign isn't priced on CPM (e.g., it's CPC), you can calculate the effective CPM (eCPM) to compare costs across different campaigns and formats:
$$\text{eCPM} = \frac{\text{Total Spend}}{\text{Total Impressions}} \times 1{,}000$$
eCPM lets you compare, for example, whether a CPC campaign or a CPM campaign delivered awareness more cost-efficiently. This is useful when evaluating impressions across different channels.