Calculator
Enter all monetary amounts in the same currency. The calculator returns ratios and amounts in that same basis.
Method and inputs
Formula: CTR = clicks / impressions; CPM = spend / impressions x 1,000; CPA = spend / conversions
Inputs: Ad spend, impressions, clicks, conversions and attributed revenue for the same campaign period.
Worked example
$1,000 spend, 50,000 impressions, 750 clicks, 30 conversions and $4,000 attributed revenue gives $20 CPM, 1.5% CTR, $1.33 CPC, 4% conversion rate, $33.33 CPA and 4:1 ROAS.
Reading the metrics together
Each metric answers a different question: CPM is the price of attention, CTR how compelling the ad is, CPC the price of a visit, conversion rate how well the landing page sells and CPA the cost of a customer. Because CPA = CPC / conversion rate, a campaign with an expensive click can still win if it converts better.
| Campaign | CPC | Conversion rate | CPA |
|---|---|---|---|
| A | $0.80 | 2% | $40 |
| B | $1.50 | 5% | $30 |
| C | $0.40 | 0.8% | $50 |
Campaign B has the most expensive clicks but the cheapest customers. Compare campaigns on CPA or ROAS over the same date range and attribution window, not on CTR alone.
Important limits
The result is only as complete as the attribution and cost data entered. It does not establish incrementality, profitability, customer lifetime value or a universally good benchmark.