SEO ROI is only useful when its revenue, cost and attribution assumptions are clear. The worked example below uses invented numbers to explain the calculation. It is not a Meridian result, a forecast or a promise about your business.
For a lead-generation site, a submitted form is not automatically a sale. Agree whether the discussion concerns qualified leads, closed revenue or contribution after variable costs. Keep those stages distinct so a change in form volume is not presented as a change in profit.
Build a cost worksheet covering agreed agency work, internal production, implementation and relevant tools. Identify which shared costs are allocated and how. Avoid adding a cost twice if it is already deducted in the margin figure used later in the model.
Suppose a team attributes $30,000 of revenue to organic search, uses a 40% contribution margin before SEO costs and spends $8,000 on SEO. Contribution is $12,000. The illustrative ROI is ($12,000 minus $8,000) divided by $8,000, or 50%. A revenue-to-cost ratio would answer a different question.
The same sale may involve organic discovery, paid retargeting and a sales conversation. Analytics attribution distributes credit under a model; it does not prove what would have happened without SEO. Compare your reporting model with CRM evidence and document gaps rather than choosing whichever figure looks largest.
If leads close later than the month in which they arrive, compare a mature lead cohort with its associated acquisition work. A scenario can vary close rate, average contribution and time to close, but each estimated input must stay labelled as an estimate.
A useful report includes the period, formula, data sources, attribution model, cost scope and unresolved questions. If revenue linkage is unavailable, report verified implementation and qualified lead stages instead of inventing an ROI percentage. Agree what evidence would make the calculation reliable next time.
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