Formula
Marketing ROI = (Incremental revenue × Contribution margin − Marketing cost) ÷ Marketing cost × 100Marketing ROI in plain English
Marketing ROI compares the net contribution caused by an activity with its marketing cost. If $10,000 of marketing cost produces $30,000 of incremental revenue at a 60% contribution margin, incremental contribution is $30,000 × 60% = $18,000. The contribution-based ROI is ($18,000 − $10,000) ÷ $10,000 = 80%.
Revenue is not always return
This calculator applies the entered contribution margin before deducting marketing cost. That adjustment prevents low-margin revenue from making a campaign appear more profitable than it is. Google Ads likewise describes ROI as a profit-to-cost measure and includes cost of goods in its worked ROI methodology.
Attribution caution
The difficult input is incremental impact: what would have happened without the marketing activity? Platform attribution, controlled experiments and blended business trends answer different questions. Document the method used whenever ROI is reported.
Assumptions
- Incremental revenue is genuinely caused by the marketing activity.
- Contribution margin includes every variable cost associated with the incremental sales.
- Marketing cost covers the same activity and period.
Sources and methodology
CalcMotive publishes the formula and assumptions so you can decide whether the estimate fits your use case. See our methodology standards.
- Google Ads Help: About return on investment; Google Ads Help; accessed Jul 13, 2026