What this calculator does
CPM stands for cost per mille, mille being Latin for a thousand: it is the price of showing an ad 1,000 times, regardless of whether anyone clicked it. Display, video and social platforms sell most of their inventory this way, because an ad can be seen without being clicked, and the advertiser is still buying that exposure.
The number people mix up is CPM versus CPC. CPM charges for reach: you pay for eyeballs on the ad, full stop. CPC charges only when someone clicks. A campaign can have a low CPM and still be a poor buy if nobody engages with the ad, and a high CPM can still be worthwhile if the audience is precisely targeted.
The formula
Divide total spend by the number of impressions delivered, then multiply by 1,000 to express it per thousand rather than per single view. The cost of one individual impression is the same figure without the ×1,000, which is normally a fraction of a cent and is shown mainly so the arithmetic is transparent.
| Term | Meaning |
|---|---|
| CPM | Cost per 1,000 impressions: (spend ÷ impressions) × 1,000. |
| Impressions | The number of times the ad was served, whether or not it was clicked or even noticed. |
| Spend | The total amount paid for the campaign or ad buy being measured. |
The inputs explained
| Field | What to enter |
|---|---|
| Total ad spend ($) | The total amount spent on the campaign, in whatever currency you track budgets in. |
| Impressions delivered | The total impressions delivered, as reported by the ad platform. |
When to use it
Comparing ad platforms
Different platforms and ad formats sell inventory at very different rates. Converting every quote to CPM puts a display banner, a social feed ad and a pre-roll video on the same footing, so a comparison is actually a comparison.
Setting a display or video budget
If a platform quotes a CPM rate, working backwards from a target number of impressions tells you the budget needed before the campaign runs, rather than finding out afterwards.
Auditing a media invoice
A vendor invoice lists spend and impressions delivered; recomputing the CPM independently checks that the delivered rate matches what was agreed.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How CPM changes as spend increases at a fixed impression volume
The same 250,000 impressions, at a range of total spend levels.
| Total spend | CPM | Cost per single impression |
|---|---|---|
| $250 | $1.00 | $0.0010 |
| $500 | $2.00 | $0.0020 |
| $1,000 | $4.00 | $0.0040 |
| $1,500 | $6.00 | $0.0060 |
| $2,500 | $10.00 | $0.01 |
| $5,000 | $20.00 | $0.02 |
How CPM changes as impressions increase at a fixed spend
A fixed $1,000 budget stretched across a range of impression volumes.
| Impressions delivered | CPM | Cost per single impression |
|---|---|---|
| 50,000 | $20.00 | $0.02 |
| 100,000 | $10.00 | $0.01 |
| 200,000 | $5.00 | $0.0050 |
| 400,000 | $2.50 | $0.0025 |
| 800,000 | $1.25 | $0.0013 |
| 1,000,000 | $1.00 | $0.0010 |
Questions
What counts as a good CPM?
It depends heavily on the platform, ad format, targeting and industry, so there is no single benchmark worth quoting. The more useful comparison is your own CPM across campaigns and platforms over time, or against a specific competing quote for the same audience.
Is CPM the same as CPC?
No. CPM charges per 1,000 impressions regardless of clicks; CPC charges only for the clicks an ad actually receives. A campaign can run on either pricing model, and the two are not directly comparable without also knowing the click-through rate.
Why do publishers prefer selling on CPM?
CPM guarantees the publisher revenue for the exposure delivered, independent of how the ad performs afterwards. That risk sits with the advertiser instead, which is why CPM buys are common for brand-awareness campaigns where clicks are not the goal.
Does a low CPM always mean a better deal?
Not on its own. A very low CPM on an irrelevant or low-quality placement can be worse value than a higher CPM against a precisely targeted audience that actually converts.
For campaigns priced on clicks instead of impressions, see the CPC calculator. To check what share of those impressions actually turned into a click, use the CTR calculator.