CPM Calculator
CheckedThis CPM calculator solves cost per thousand impressions, total ad spend or impressions: enter any two and it finds the third. Free, no sign-up, and the result updates as you type.
Enter your numbers
The M in CPM is the Roman numeral for a thousand, not million, and forgetting it is an off-by-1000 error that turns a $13.60 CPM into a $0.0136 one. The relationship has three terms — spend, impressions and CPM — so fixing any two gives the third, which is how you check whether a publisher's quoted rate matches the inventory they are promising. Pick the unknown below and the other two fields solve it in either direction.
How it's calculated
CPM = ad spend × 1000 ÷ impressions Spend = CPM × impressions ÷ 1000 Impressions = ad spend × 1000 ÷ CPM
LaTeX source
\text{CPM} = \frac{S \times 1000}{I} \qquad S = \text{CPM} \times \frac{I}{1000} \qquad I = \frac{S \times 1000}{\text{CPM}} Worked examples
Working out the CPM you actually paid
$13.60 CPM
$850 across 62,500 impressions is $850 × 1000 ÷ 62,500 = $13.60 per thousand. Per single impression that is $0.0136, just over a cent. If the insertion order promised a $12.50 CPM, the flight delivered 8.1% fewer impressions than it was paid for and the publisher owes make-goods.
The numbers used
- Solve for
- cpm
- Ad spend
- 850
- Impressions
- 62500
- CPM
- 12.5
Sizing a budget against a quoted rate
160,000 impressions
At a $12.50 CPM, $2,000 buys $2,000 × 1000 ÷ 12.50 = 160,000 impressions. Against a 25,000-person target list that is roughly six impressions each, which is enough frequency to fatigue the creative — a useful sanity check before signing, and one the spend figure alone will never show you.
The numbers used
- Solve for
- impressions
- Ad spend
- 2000
- Impressions
- 0
- CPM
- 12.5
Questions sellers ask
How do you calculate CPM?
Multiply ad spend by 1,000 and divide by impressions. $850 across 62,500 impressions is a $13.60 CPM. The multiplication by a thousand is the whole trick: CPM prices a batch of a thousand impressions because the per-impression figure, $0.0136 here, is too small to compare at a glance. Going the other way, spend equals CPM × impressions ÷ 1,000.
Is $20 CPM high?
It is high for broad display and low for narrow B2B or connected TV. Programmatic display often clears in the $2 to $10 range, Meta prospecting commonly runs $8 to $20, LinkedIn by job title regularly exceeds $40, and CTV sits around $25 to $45. What matters is the CPM against the conversion rate behind it: a $20 CPM at a 2% CTR is a $1.00 CPC, which is cheaper than a $6 CPM at a 0.3% CTR.
What is CPM and how to calculate it?
CPM is cost per mille — the price of one thousand ad impressions — calculated as spend × 1,000 ÷ impressions. It is the standard unit for buying awareness inventory, where advertisers pay for the ad being shown rather than clicked. Use it to compare placements on raw delivery cost, then convert to CPC or CPA before deciding which placement actually earned its budget.
How much does CPM cost per 1000 views?
The CPM is the cost per 1,000, so no further arithmetic is needed: a $13.60 CPM is $13.60 for a thousand impressions. Beware the word views, though. Platforms count an impression when an ad is served, which is not the same as a viewable impression under the IAB standard of 50% of pixels for one second, and video views have their own thresholds again.
How do I calculate eCPM?
Divide total revenue by impressions and multiply by 1,000. A publisher earning $340 from 62,500 impressions has a $5.44 eCPM. It is the same formula as CPM with earnings in place of cost, which is why it is called effective CPM — it normalises income from CPC, CPA and revenue-share deals into a single comparable thousand-impression rate.
What is eCPM vs CPM?
CPM is what a buyer pays; eCPM is what a seller earns, restated per thousand impressions. They describe the same inventory from opposite sides of the transaction, and they never match, because the ad network keeps a cut between them. A publisher comparing a $5.44 eCPM ad unit against a $6.10 one is doing the same job as a buyer comparing two CPMs.
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