eCommerce Revenue Calculator
Online revenue is three numbers multiplied together: sessions, conversion rate and average order value. Writing it that way is what turns a target into a plan, because it forces you to say which of the three is supposed to move — and a target that needs all three to improve at once is usually a target nobody has checked.
INPUTS
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FORMULA
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Sessions times conversion rate times order value. Every revenue plan is a claim about one of those three.
- The calculator
Revenue built from its parts, then projected forward
The first three inputs produce this month. The next three turn it into a forecast you can argue with. Everything recalculates as you type and nothing leaves your browser.
Revenue = sessions × conversion rate × average order value. The projection compounds that first month at your growth rate and sums the series: month × ((1 + g)n − 1) ÷ g, or simply month × n when growth is zero. Revenue per session is conversion rate × order value, which is the cleanest way to judge whether a traffic source is worth its cost — if a channel costs more per click than a session is worth, no amount of volume fixes it. Two things this deliberately does not model: seasonality, which can swing a single month by more than a year of compound growth, and the fact that traffic bought at scale usually converts worse than the traffic you have now.
- Reading it
Three inputs, and only one of them is cheap to move
The equation is simple. Deciding which term the plan depends on is the whole job.
Sessions, conversion rate and order value each produce revenue in exactly the same proportion — ten per cent on any of the three is ten per cent on the top line. What differs enormously is what each costs to get. Sessions are bought and stop the moment you stop paying. Conversion rate and order value are earned once and then apply to every session you ever buy afterwards, including the ones you already paid for.
That is why revenue per session is the tile worth watching. At the defaults it is $1.80, which means any traffic costing more than that per visit loses money before a single fixed cost is counted. Raise conversion from 2.2% to 2.5% and revenue per session becomes $2.05, and every channel that was marginal becomes viable. A plan that reaches its target by adding sessions alone is the most expensive version of the same number.
- Write the target as all three terms before agreeing to it
- Sense-check the growth rate against the last twelve months, not the plan
- Model a flat month as well — compound forecasts hide a lot
- Getting it wrong
Four ways a revenue forecast stops being useful
Each of these produces a number that compounds neatly and describes nothing.
Compounding a growth rate nobody achieved
Three per cent a month is 43% a year, and five per cent is 80%. Rates that look modest in a cell become heroic over twelve. Take the rate from your own last twelve months before you take it from the plan.
Ignoring seasonality entirely
A November that does three times an average month makes a smooth compound curve meaningless. Run the forecast on a normalised month and treat peak separately, or the first quarter will look like a miss that never was.
Assuming bought traffic converts like current traffic
The sessions you have now are the cheapest and best-qualified you will ever get. Doubling volume almost always lowers the blended conversion rate, so a forecast that holds it constant overstates the answer twice over.
Forecasting revenue and calling it profit
Revenue growth bought at a contribution margin thinner than the cost of acquiring it is how stores get bigger and poorer at the same time. The contribution tile is here so the two numbers stay in the same view.
Our conversion rate calculator shows which funnel step is holding the middle term down, and the average order value calculator does the same for the third.
- Questions
Revenue forecast FAQs
The questions this calculator usually raises.
How do you calculate eCommerce revenue?
Sessions multiplied by conversion rate multiplied by average order value, over the same period for all three. Writing it as three terms rather than one number is the point: it makes every revenue plan state which term is supposed to move, and by how much. A target that quietly requires all three to improve simultaneously is usually a target that has not been checked against anything.
What growth rate should I use?
Your own, measured over the last twelve months rather than taken from the plan. Compute it as the twelfth root of this month divided by the same month last year, minus one. If that produces a number you do not like, the honest response is to change what the business does rather than the cell — a forecast built on a rate nobody has hit is just a longer way of writing a wish.
Why is revenue per session the important number?
Because it is the only figure here you can compare directly against what traffic costs. At $1.80 a session, any channel priced above that loses money before a single overhead is counted. It also improves for free every time conversion rate or order value rises, which is what makes CRO and merchandising compound in a way that buying more traffic never does.
Does this forecast handle seasonality?
No, deliberately. A smooth compound curve through a November peak is worse than useless, because the first quiet month afterwards reads as a failure. Run the calculator on a normalised month, plan peak trading separately, and compare actuals to the same month last year rather than to the curve.
How is this different from the PPC budget calculator?
Opposite directions. This one starts with the traffic and conversion you have and tells you what revenue they produce. The PPC budget calculator starts with a revenue target and tells you what paid media it would take to get there. Use this one to find a realistic number, that one to cost it.
Should I forecast in revenue or contribution?
Both, which is why the last tile exists. Revenue sets the operational plan — stock, staffing, fulfilment capacity — while contribution is what actually funds the business. If you only ever look at one of them in a planning meeting, look at contribution, because revenue grown below the cost of acquiring it is how a store gets larger and less solvent at the same time.
- Next
Related tools and reading
CALCULATOR
The middle term, broken into four funnel steps so you can see which one is holding revenue down.
CALCULATOR
The same equation run backwards: start from a revenue target and find the paid media it needs.
GUIDE
The growth equation, the stages, cash and forecasting cadence — the management view behind this number.
Forecast built, confidence low?
It usually comes down to whether the growth rate and the conversion rate are real. The free audit checks both against your own twelve months before the plan gets committed to.