Free calculator
Market size calculator: a TAM investors will believe
Top-down market sizes from analyst reports get ignored. Enter how many customers exist, how many you can reach, what they would pay and what share you can realistically win, and the calculator gives you TAM, SAM and SOM bottom-up.
TAM, SAM and SOM in one sentence each
TAM is every customer who could use the product times what they would pay per year. SAM is the part you can serve with today’s product, geography and channel. SOM is the share of SAM you can win in three to five years given competition and your sales capacity.
Why bottom-up wins the meeting
A number built from customers times price can be checked: the investor can disagree with a single assumption rather than the whole slide. “Two million small restaurants in Europe at $1,200 a year” is a conversation. “A $40B market growing 12 percent” is not.
Common mistakes
Using the whole TAM as if it were reachable, pricing at the enterprise tier while selling to SMBs, and claiming 10 percent of a market with no channel that gets you there. The plausibility check in the calculator compares your target with the SOM.
The beachhead
Investors want to see the first segment, not the end state. Name the beachhead, size it, show the share you can win there, then show how the same product expands. The copyable summary is written in that order.
Questions founders ask
What counts as a customer?
Whoever signs the contract and pays. For marketplaces, size the paying side first.
Should I use ARPU or list price?
Use what customers actually pay today, or the price you have validated in conversations. Not the price you hope for.
Is a small TAM a deal breaker?
For venture capital, a SAM below $1B usually is. For angels, accelerators and non-dilutive funding, it often is not.
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