SEO ROI calculator: SEO vs Google Ads

How the calculator works

The model starts with a group of keywords and the position you are aiming for in Google. Monthly search volume multiplied by the average click-through rate (CTR) of that position gives the estimated number of organic clicks. Multiply the same clicks by the cost per click (CPC) in Google Ads and you see what you would pay to buy that traffic. The clicks then pass through your conversion rate, average order value and margin to arrive at monthly gross profit.

Rankings aren't won overnight, so the model grows traffic gradually along an S-shaped curve until the month you choose, then treats it as stable. The full SEO budget is counted every month, including after you reach the target position, because rankings have to be defended.

How to read the results

• Equivalent Google Ads cost does not mean Ads would bring in exactly the same customers; it is what the same volume of clicks would cost. Treat it as a yardstick for the value of organic traffic.
• ROI at 12 and 24 months = (cumulative profit − cumulative SEO cost) ÷ cumulative SEO cost. A negative ROI at 12 months is common in SEO; where the curve ends up afterwards matters just as much.
• Break-even is the first month in which cumulative profit reaches the total invested. It is marked with a dot on the green line.

Where to get realistic inputs

• Search volume comes from Google Keyword Planner or, for queries you already rank for, from Google Search Console. Group close variants together, and use the question and keyword generator for ideas.
• CPC is also in Keyword Planner (the top-of-page bid range) or directly in your Google Ads account.
• Conversion rate comes from your analytics tool (for example Google Analytics): how many organic visitors submit a form, call or buy.
• Average order value and margin come from your sales and accounting. For services with repeat customers, use a customer's first-year value.

The full method is described in our guide to keyword research. Once a campaign is running, track the same numbers monthly; SEO KPIs and what a useful monthly report looks like shows what to measure.

The limits of the model

Real CTR can be far below the average when ads, a map pack, shopping results or an AI Overview appear above the organic listings, which is why you can edit the curve and switch on an AI Overview reduction. Many niches are also strongly seasonal. A single keyword group does not represent a whole website: a good strategy covers many groups, and the effort is shared between them. Above all, nobody can guarantee a ranking in Google; the calculator shows what a position would be worth, not that you will get it.

SEO and Google Ads are not mutually exclusive

Google Ads delivers traffic from day one and helps you learn quickly which keywords bring customers. SEO builds an asset that can keep bringing visits after the work has been paid for. Most businesses do best by combining them, using Ads data to decide where an SEO investment is worth making. To see what this means in money for your business, read how much SEO costs, take a look at our SEO services, or ask for an analysis based on your own data.