CPM Calculator
This CPM calculator works out the cost per thousand impressions of an ad campaign, or solves for the budget or the number of impressions when you know the other two. Add clicks, conversions and revenue if you have them, and it also returns click-through rate, cost per click, cost per acquisition, return on ad spend and eCPM, so you can compare campaigns that are priced in different ways.
Updated
Results
- Click-through rate (CTR)Clicks ÷ impressions
- Cost per click (CPC)
- Conversion rateConversions ÷ clicks
- Cost per acquisition (CPA)Cost ÷ conversions
- ROAS (revenue per $1 of ad spend)Revenue ÷ cost
- ROI on ad spend(Revenue − cost) ÷ cost
- Revenue minus ad costBefore product and other costs
- eCPM (revenue per 1,000 impressions)Publisher view
Results are estimates. See the methodology below.
How to use the calculator
- Pick what to solve for: CPM, total cost or impressions. The field you solve for disappears and becomes the result.
- Enter the two known values. Cost is your total ad spend in dollars; impressions are the number of times the ad was shown; CPM is the price per 1,000 impressions.
- Add optional performance data. Clicks unlock CTR and CPC. Conversions (with clicks) unlock conversion rate and CPA. Revenue unlocks ROAS, ROI, profit on ad spend and eCPM. Leave a field empty and its results stay hidden.
Use figures from the same date range and the same campaign in your ad platform's report, or the ratios won't line up.
Formulas
The M in CPM stands for mille, Latin for thousand. The three core values are linked by one equation:
CPM = cost ÷ impressions × 1,000
So cost = CPM × impressions ÷ 1,000, and impressions = cost ÷ CPM × 1,000. The optional metrics:
- CTR = clicks ÷ impressions
- CPC = cost ÷ clicks
- Conversion rate = conversions ÷ clicks
- CPA = cost ÷ conversions
- ROAS = revenue ÷ cost, shown as a multiple: 3.60 means $3.60 of revenue per $1 spent. Google Ads writes the same ratio as a percentage (360%).
- ROI = (revenue − cost) ÷ cost
- Profit = revenue − ad cost. This is before the cost of the product, shipping, fees and staff, so it is not your real profit.
- eCPM = revenue ÷ impressions × 1,000, the publisher's view: what each thousand impressions earned rather than cost.
Worked examples
1. A full campaign report
You spent $750 on 150,000 impressions. CPM = $5.00. The ad got 1,200 clicks and 36 sales worth $2,700 in total:
| Metric | Result |
|---|---|
| CTR | 0.80% |
| CPC | $0.63 |
| Conversion rate | 3.00% |
| CPA | $20.83 |
| ROAS | 3.60 |
| ROI | 260.0% |
| Revenue minus ad cost | $1,950.00 |
| eCPM | $18.00 |
2. Planning a budget
A placement is sold at a $12 CPM and you want 250,000 impressions: the cost is $3,000.00. Turn it around: with $2,000 at an $8 CPM you can buy 250,000 impressions.
3. A higher CPM can be the better deal
Compare the first campaign with a second one that cost $3,000 for 250,000 impressions and drew 6,250 clicks. Its CPM is $12.00, more than twice as high, but its CTR is 2.50% and each click costs $0.48 instead of $0.63. If you pay for impressions but care about clicks or sales, compare CPC and CPA, not CPM alone.
Why CPM varies
Much digital ad space is sold through auctions, so CPM reflects competition for the audience you target rather than a fixed price list. The audience, the placement, the ad format and the time of year can all move it, and so can how people respond to the ad. That is why a single average CPM is of little use: compare your own campaigns over time, on the same platform and objective.
Frequently asked questions
How do you calculate CPM?
Divide the total cost by the number of impressions and multiply by 1,000. For $750 and 150,000 impressions: $750 ÷ 150,000 × 1,000 = $5.00 per thousand impressions.
What is the difference between CPM and CPC?
CPM is the price of 1,000 impressions, whether or not anyone clicks. CPC is the cost of each click. You can turn one into the other with CTR: in the first example, a $5.00 CPM with a 0.80% CTR gives a CPC of $0.63.
What is eCPM?
Effective CPM is revenue per 1,000 impressions. Publishers use it to compare earnings from ads sold on different terms (per click, per action, flat fee). In the first example, $2,700 of revenue over 150,000 impressions is an eCPM of $18.00.
What does a ROAS below 1 mean?
The ads brought in less revenue than they cost. If the first campaign had produced only $180 in sales, ROAS would be 0.24, ROI −76.0% and revenue minus ad cost −$570.00. Even a ROAS above 1 can lose money once product and other costs are paid.
What is viewable CPM (vCPM)?
With vCPM bidding you pay only for impressions where the ad could actually be seen, as Google Ads describes it. The formula is the same; just enter viewable impressions instead of all impressions.
Why do I get an error about clicks?
Clicks can't exceed impressions in the same report, since every click needs an ad view. Check that both numbers come from the same campaign and date range.
Sources
This calculator is for planning and reporting purposes only. Results depend entirely on the figures you enter and do not predict how a campaign will perform.