How the calculation works
Monthly customers = extra visitors × conversion rate × close rate
Monthly revenue = customers × customer value (gross profit if you enter a margin)
ROI = (total return − total SEO cost) ÷ total SEO cost
Traffic is assumed to grow in a straight line from zero to your full figure over the ramp-up period, then stay there. Payback is the month in which cumulative return first exceeds cumulative cost. If you enter a margin, return is calculated on gross profit rather than revenue, which is the honest comparison.
Choosing realistic inputs
- Extra visitors: base this on real search demand for your services and areas, not on hopes. A local service business might reasonably target hundreds of extra visits a month; a national ecommerce site, thousands.
- Conversion rate: your current organic conversion rate from analytics is the best starting point. Service sites often convert 2–5% of organic visitors into enquiries.
- Ramp-up: local SEO often shows movement in 3–6 months; competitive national terms can take 6–12 months or more. See how long local SEO takes to work.
What makes SEO ROI different
Unlike ads, organic traffic does not stop the day you stop paying. Rankings built on a strong site tend to keep producing traffic for some time, so a 12-month view usually understates the long-term return. On the other hand, traffic that does not convert is worth nothing: if visitors arrive and do not enquire, read where SEO breaks down between traffic and leads, and check your conversion rate with the Website Conversion Rate Calculator.
Limitations
This is a model of your assumptions, not a forecast. It cannot know your competition, your site’s current authority or how search results will change. Use it to decide whether SEO could plausibly pay back, and to compare budgets, not as a promise of results.