Five numbers you already have, and the arithmetic that turns a traffic conversation into a money conversation. It runs in your browser, sends nothing anywhere, and tells you the break even point as well as the upside.
At your own numbers, one organic session is worth £15.00. That single figure is the one worth writing down, because it turns every traffic decision into a money decision.
£6,000
extra a month
£15,000
extra a month
£30,000
extra a month
Organic sessions would need to rise 8.3% before £2,500 a month pays for itself.
That is 167 more sessions a month. Whether that is realistic depends on your market, your starting position and how long you give it. Anyone who tells you the number without asking those questions is guessing.
This is arithmetic on the five numbers you entered, not a forecast. It does not predict that traffic will rise, or say how long that would take, and no tool that has never seen your site can tell you either. What it does is turn a traffic conversation into a money conversation, so you can judge whether the work is worth commissioning at all.
Most people arrive at SEO thinking about rankings, then traffic, then eventually revenue. That order makes the work impossible to judge, because a ranking has no price attached to it.
Running the arithmetic backwards fixes it. Once you know what a single organic visit is worth at your own conversion and close rates, every decision below it becomes arithmetic rather than faith.
The break even figure is the honest half. It says how much more traffic would have to arrive before a given monthly spend covers itself. If that number is small, the case is easy. If it is large, you have learned something valuable for free.
A calculator that only ever produces an encouraging answer is a sales tool, not a calculator.
No, and be wary of any calculator that says it is. This is arithmetic on five numbers you supply. It shows what a given traffic increase would be worth at your own conversion rate, close rate and customer value. It does not claim that increase is achievable, or say how long it would take, because no tool that has never seen your site can know either.
Organic sessions a month, from Search Console or your analytics, not total traffic. Mixing paid and direct traffic in makes every figure below it wrong, usually in a flattering direction.
Divide the enquiries you got last month by the sessions you got last month. If you cannot get either number, that is the first problem to fix, and it is a measurement problem rather than a traffic one.
The whole relationship. Using the first invoice understates everything and makes almost any marketing look unaffordable. Using an optimistic lifetime figure does the opposite, so be conservative if you are unsure.
Because it is the question a buyer actually has, and most calculators leave it out because the answer is sometimes uncomfortable. If the traffic increase needed to cover the cost is implausible for your market, you are better off knowing that before you commission anything.