The SEO ROI formula
SEO ROI = (return from SEO − cost of SEO) ÷ cost of SEO × 100. If you spend $18,000 in a year and organic search brings in $45,000 of added gross profit, the ROI is (45,000 − 18,000) ÷ 18,000 = 150%.
Return here means the extra value from organic traffic you wouldn't have had otherwise, not all organic revenue. That's why the calculator works on the gap between your current traffic and your goal.
How the calculator works
Each month in the period it does the same four steps.
- 1Works out added visits: the gap between today's traffic and your goal, ramped evenly until the goal month, then held
- 2Multiplies added visits by your conversion rate to get added conversions
- 3Multiplies conversions by value per conversion to get added revenue, and by your margin if you entered one
- 4Adds it to the running total and compares it with your running cost to find the break-even month
Where to find your inputs
Use real data where you have it.
- Current organic visits
- Google Analytics 4 (Reports, Acquisition, Traffic acquisition, filtered to Organic Search) or clicks in Google Search Console's Performance report.
- Conversion rate
- Conversions from organic sessions divided by organic sessions, from GA4 for the last few months. Use your own figure rather than a published average.
- Value per conversion
- Average order value for e-commerce. For leads, multiply lead-to-customer rate by average deal size, or use customer lifetime value if you track it.
- Monthly cost
- Everything SEO costs: agency or freelancer fees, tools, content and the share of staff time spent on it.
- Traffic goal
- Base it on the search volume of keywords you can realistically win, not a round number.
How long does SEO take to pay off?
There's no honest single answer. It depends on your site's authority, the competition for your keywords and how much you publish. Google's own guidance has long said it can take months for changes to show results. That's why the ramp and the period are inputs: try a slower ramp and see whether the investment still breaks even inside a time frame you can accept.
Revenue ROI vs profit ROI
ROI on revenue looks bigger, but a sale that earns $100 of revenue and costs $70 to fulfil only returns $30. If you're comparing SEO with ads or other investments, enter your gross margin so every channel is measured on profit.
What the calculator leaves out
A simple model is easy to check. It also ignores a few things worth mentioning in a business case.
- Value that lasts after you stop spending: rankings often hold for months
- Brand awareness and assisted conversions that start with an organic visit
- Seasonality and algorithm updates, in either direction
- Traffic that would have grown anyway without SEO work
- Organic clicks lost to AI answers that cite you without a visit
Using it to set an SEO budget
Work backwards. Set your conversion rate and value, pick a realistic traffic goal, then raise the monthly cost until break-even lands at the month you can tolerate. That cost is the most you can spend for that goal. If the number is too low for the work needed, the goal or the timeline needs to change.