Market sizing calculator
TAM, SAM and SOM are the same market narrowed twice: every account that could ever buy, the slice you can actually sell to, and the share you could realistically win. Bottom-up — accounts multiplied by price — is the only version anyone experienced believes.
The working
Every row computed from your inputs.
| Layer | Customers | Revenue | What it means |
|---|---|---|---|
| TAM | 900,000 | €259,200,000 | Everyone with the problem |
| SAM | 108,000 | €31,104,000 | Those you can sell to |
| SOM | 3,240 | €933,120 | Those you could win |
Market sizing, step by step
TAM is the number of accounts in the world with the problem, multiplied by what they would pay a year. SAM narrows that to the ones you can reach and serve: the right geography, the right size, the right language, a product that actually works for them. SOM narrows again to what you could win in a defined period given your sales capacity and the competition already there.
Each narrowing needs a stated reason and a number. "We can serve 30% of the market" is not a reason. "We sell in English and only to companies above 50 seats, which is 12,000 of the 80,000 accounts" is one, and it survives a question.
Where this number misleads you
Top-down sizing — taking an analyst’s market figure and claiming 1% of it — is the version investors have learned to discount entirely, because 1% of a large number can be made to look like anything. It also hides the only question that matters: whether there are enough reachable accounts to build a business before you run out of money.
Questions people ask
How do I calculate TAM?
Bottom-up: count the accounts in the world that have the problem you solve, and multiply by realistic annual revenue per account. Use a real source for the count — an industry register, a company database, census data — and state it. Avoid taking a published market figure and claiming a percentage of it.
What is the difference between TAM, SAM and SOM?
TAM is everyone who could ever buy. SAM is the part you can actually sell to and serve today, given your geography, segment and product. SOM is what you could realistically capture in a stated period, given your sales capacity and who is already there. Each step needs a named reason.
Should I use top-down or bottom-up market sizing?
Bottom-up, for anything you will be questioned on. Top-down sizing starts with someone else’s market number and applies a share you cannot justify; bottom-up starts with countable accounts and a price, so each assumption can be challenged separately. Use top-down only as a sanity check on the bottom-up answer.
When one number is not the job
This page works out one number. PikoPM’s Business model canvas puts the number in the argument around it, which is what an investor or a board actually reads.
Open Business model canvas — it needs an account, and the Free plan covers it.