The Complete Guide to CPM (Cost Per 1,000 Impressions)
By Arshi Khan, Founder of Just4Marketing · Last reviewed October 2026
CPM tells you what it costs to put your ad in front of 1,000 people, making it the standard way to compare the price of reach across ad platforms. This guide covers the formula, how to solve for cost or impressions, and rough CPM ranges by platform.
What is CPM and why does it matter?
CPM = (Total cost ÷ Impressions) × 1,000 — literally, the cost to reach a thousand people. Because it's normalized to a fixed audience size, CPM lets you compare the price of reach across campaigns and platforms even when total spend and audience size differ wildly.
The same formula rearranges to solve for cost (CPM × impressions ÷ 1,000) or impressions ((cost ÷ CPM) × 1,000), which is useful when you're planning a campaign around a fixed budget or a fixed reach target.
Rough CPM benchmarks by platform
These are commonly cited rough ranges — actual CPMs shift with audience targeting, seasonality, and competition:
| Platform / format | Typical CPM (rough) |
|---|---|
| Display / banner ads | $2 – $10 |
| Social media feed ads | $5 – $15 |
| Video ads (pre-roll) | $10 – $30 |
| Connected TV / streaming | $20 – $50+ |
Key considerations
CPM measures reach cost, not effectiveness
A cheap CPM with a poor click-through or conversion rate can end up costing more per outcome than a pricier CPM on a higher-quality placement — always look at CPM alongside downstream metrics.
Audience targeting drives price more than format
Highly specific or in-demand audience segments command higher CPMs regardless of ad format, since you're competing with other advertisers for the same attention.
CPM fluctuates with seasonality
Advertiser demand spikes around major shopping periods (like Q4 in many markets), pushing CPMs up across most platforms during those windows.
Compare CPM within the same platform when possible
Cross-platform CPM comparisons can be misleading since ad formats, viewability standards, and audience quality differ — CPM is most reliable for comparing options within one platform.
Frequently asked questions
What's the difference between CPM and CPC?
CPM charges for reach — you pay per 1,000 impressions regardless of clicks. CPC charges per click, regardless of how many impressions it took to get that click. CPM suits awareness goals; CPC suits direct-response goals where you care most about traffic.
How do I figure out how many impressions my budget buys?
Solve for impressions: divide your total budget by the CPM, then multiply by 1,000. For example, a $500 budget at a $5 CPM buys (500 ÷ 5) × 1,000 = 100,000 impressions.
Why do CPMs vary so much between platforms?
CPM reflects supply and demand for attention on that platform and audience — video and highly-targeted audiences tend to command higher CPMs than broad display placements, and competition for a given audience segment pushes CPMs up regardless of format.
Is a lower CPM always better?
Not necessarily. A very low CPM often means low-quality or low-attention placements. It's more useful to weigh CPM against downstream performance — click-through rate and conversion rate — rather than optimizing for the cheapest impressions alone.