Choose the value definition
Revenue is not profit. For this guide, contribution means incremental revenue multiplied by an appropriate contribution margin before subtracting the marketing investment. Agree the cost basis with finance so fulfillment, discounts or other costs are not counted twice or omitted.
The equation is: marketing ROI = (incremental revenue × contribution margin − marketing investment) ÷ marketing investment. Express margin as a decimal and ROI as a percentage. A zero investment makes this ratio undefined.
Work a hypothetical example
| Input | Illustrative value |
|---|---|
| Incremental revenue | $100,000 |
| Contribution margin before marketing | 60% |
| Marketing investment | $30,000 |
| Incremental contribution | $60,000 |
| Contribution after marketing | $30,000 |
| ROI | 100% |
These values explain the arithmetic. They are not NCMC results, expected returns or industry benchmarks. At a 30% contribution margin, the same revenue and investment would produce 0% ROI under this equation.
Do not substitute credited revenue silently
Attribution allocates credit among observed touchpoints. Incremental revenue asks what changed because of the activity. Google’s attribution documentation describes the first; its Conversion Lift documentation illustrates controlled comparisons for the second. If your input is attributed revenue, call the output an attribution-based scenario rather than a measured causal return.
Include the relevant costs
Consider media, external fees, production, technology and the internal effort attributable to the program. Define whether sales handling is included and use a consistent approach across comparisons. Do not compare a media-only denominator with a fully loaded program cost and call the difference performance.
Align the period
Use an observation window suited to the buying and revenue process. A campaign’s cost can occur before its revenue. Recent cohorts may be immature; long windows can introduce other influences. Record the period, recognition basis and unresolved assumptions.
Use sensitivity, not false precision
Calculate a conservative, central and optimistic case for uncertain revenue, margin or cost. Identify which assumption changes the decision most. The calculator in this library makes those inputs explicit and shows break-even revenue. A precise output is only as reliable as the evidence and definitions behind the inputs.