What the Market Size Calculator Does
This Market Size Calculator gives you a fast, top-down estimate of how many customers you could realistically reach and how much revenue that audience represents. It takes three simple inputs — your target population, the share of that population you expect to win, and how much each customer pays — and turns them into two clear numbers: total customers and total revenue. It works in any currency or country; the dollar sign is just a label, so feel free to read it as your local currency.
The Inputs Explained
- Target Population: The total number of people or businesses that could potentially buy your product — your addressable audience, not the whole world.
- Penetration Rate (%): The realistic percentage of that population you expect to convert into paying customers.
- Average Revenue per Customer ($): The typical amount one customer spends — annually, monthly, or per purchase, depending on the period you choose to model.
The Formula
The calculator works in two steps. First it finds the number of customers, then it multiplies by spend per customer:
- Total Customers = Target Population \(\times\) (Penetration Rate \(\div\) 100)
- Total Revenue = Total Customers \(\times\) Average Revenue per Customer
Combined, this is: $$\text{Total Revenue} = \text{Target Population} \times \frac{\text{Penetration Rate}}{100} \times \text{Average Revenue}$$.
Worked Example
Suppose you sell project-management software to small businesses. You estimate a target population of 500,000 firms, a realistic penetration rate of 2%, and an average revenue of $300 per customer per year.
- $$\text{Total Customers} = 500{,}000 \times \frac{2}{100} = 10{,}000 \text{ customers}$$
- $$\text{Total Revenue} = 10{,}000 \times \$300 = \$3{,}000{,}000$$
So your estimated annual market is 10,000 customers worth $3 million.
Frequently Asked Questions
What's a realistic penetration rate? For new entrants in competitive markets, 1–5% is common; established leaders may reach 20% or more. It's safer to model conservative and optimistic scenarios.
Is this TAM, SAM or SOM? Using your full target population gives a serviceable market figure; applying a penetration rate narrows it toward your obtainable market (SOM). Adjust the population input to switch views.
Annual or lifetime revenue? That depends on the average revenue figure you enter. Use yearly spend for an annual market size, or customer lifetime value for a total opportunity estimate.
