Market Size Calculator
Enter how many potential customers there are, what each spends a year, the share you can serve and the share you can realistically win. The calculator gives your total, serviceable and obtainable market and the customers that means.
- TAM, SAM and SOM
- Bottom-up method
- Customers and revenue
Serviceable share means the customers your product, region and channels can reach. Obtainable share is what you can win in three to five years.
Investors ask three questions about any market. How big is it in total (TAM), how much of it can you actually serve (SAM), and how much can you win in the next few years (SOM)? A bottom-up estimate starts with real customer numbers and prices.
Market size examples
Bottom-up estimates. Search for a market.
| Market | Customers | Spend a year | SAM | SOM | SOM value |
|---|---|---|---|---|---|
| Local gym | 50,000 | $600 | 20% | 10% | $600 k |
| Pet food app | 2,000,000 | $60 | 25% | 4% | $1.2 m |
| B2B software | 40,000 | $5,000 | 30% | 5% | $3 m |
| Online course | 5,000,000 | $50 | 10% | 2% | $500 k |
These are made-up examples to show the method, not real market data.
Obtainable share and SOM
1 million customers at $100. Slide the obtainable share.
The circles are drawn to scale by area. The smallest is the market you can win.
How to size a market
From the bottom up. Step through it.
Count customers
Who could buy.
A top-down figure from an industry report is a good cross-check, but investors trust bottom-up numbers more.
Top-down, bottom-up or value theory
Methods. Compare them.
From industry totals.
From customers and price.
From the value you create.
Use two methods and see whether they roughly agree. If they do not, find out why.
Before presenting
Pitch checks. Tick each item.
Tick each item as you go.
Say where every number comes from. A sourced, modest SOM is more convincing than a huge TAM.
What you get
Market sizing. Each tile explains one result.
Total market.
You can serve.
You can win.
At SOM.
Revenue at SOM.
Show the three circles on one slide, with the SOM as the number you plan to hit.
Frequently Asked Questions
No question matches that search.
What is TAM, SAM and SOM?
Total addressable market, serviceable available market and serviceable obtainable market: the whole market, the part you can serve and the part you can win.
How do I calculate TAM?
Multiply the number of potential customers by what each spends a year.
What is a good SOM percentage?
Often 1% to 10% of SAM for a new business over three to five years.
What is the difference between top-down and bottom-up market sizing?
Top-down starts from industry totals. Bottom-up builds from customer numbers and price.
Why do investors want SOM?
It shows the revenue you can realistically reach, not just how big the industry is.
Where can I find customer numbers?
Census data, trade bodies, industry reports and your own survey results.
Should SAM include only my region?
Yes, if you can only sell there today. Grow it as you expand.
A market size you can defend
Build up from real customers and prices, narrow to what you can serve and win, and show where every number comes from.
More size calculators
Each one has its own calculator, worked examples and answers to common questions.