CPM, CPC, CTR and CPA Calculator
By Santaji GadepatilinUpdated October 27, 2026
CPM, CPC, CTR and CPA are the basic metrics of digital advertising. They show how much your ads cost and how well they turn impressions into clicks and customers.
How to use the CPM, CPC, CTR and CPA calculator
Enter ad spend, impressions, clicks and conversions from your ad platform. The calculator gives CPM, CPC, CTR, conversion rate and CPA together. You can also work backwards — for example, enter a target CPA and press × on Ad spend to see the budget for a number of conversions.
CPM, CPC, CTR and CPA formulas
| Metric | Formula |
|---|---|
| CPM | Spend ÷ Impressions × 1,000 |
| CPC | Spend ÷ Clicks |
| CTR | Clicks ÷ Impressions |
| Conversion rate | Conversions ÷ Clicks |
| CPA | Spend ÷ Conversions |
The ad funnel
Each metric is one step in the funnel:
Impressions → (CTR) → Clicks → (Conversion rate) → Conversions
Improving any step lowers CPA. A 20% better CTR and a 20% better conversion rate together cut CPA by about 31%.
Typical ranges (rough guide)
| Channel | CTR | Conversion rate |
|---|---|---|
| Search ads | 3–6% | 3–8% |
| Social feed ads | 0.5–1.5% | 1–5% |
| Display banners | 0.1–0.5% | 0.5–2% |
| 1–4% | 1–5% |
Benchmarks vary widely by industry, country and offer — compare against your own history first.
Example
500 spent, 100,000 impressions, 1,500 clicks, 45 conversions:
- CPM = 5.00, CPC = 0.33, CTR = 1.5%
- Conversion rate = 3%, CPA = 11.11
From CPA to profit
A campaign is profitable when CPA is below the profit from each conversion. Use the ROAS calculator for revenue-based campaigns and the customer lifetime value calculator when customers buy repeatedly.
Frequently asked questions
How do I calculate CPM?
CPM = ad spend ÷ impressions × 1,000. 500 spent for 100,000 impressions is a CPM of 5.
What is a good CTR?
It varies by platform and industry. Search ads often see 3–6%, while display and social ads are commonly under 1–2%.
How are CPC, CTR and CPM related?
CPC = CPM ÷ (CTR × 1,000). A 5 CPM with a 1.5% CTR gives a CPC of about 0.33.
What is the difference between CPA and CAC?
CPA is the ad cost per conversion (which may be a lead or a sale). CAC includes all sales and marketing costs to win a paying customer.