TAM SAM SOM Calculator
Build a defensible market size from the bottom up: total addressable market, serviceable available market and realistic obtainable share, with the assumptions shown rather than hidden.
Last reviewed by the Radiatus Cloud team
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Top down market sizing convinces nobody
"The global market is worth 50 billion and we only need one percent" is the single most reliably rejected slide in venture pitching. It fails because the number is unfalsifiable and the one percent is arbitrary, and because the person reading it has seen the same slide from every company in the category. A bottom up calculation, built from a countable population multiplied by a real price, is checkable and therefore credible even when the resulting number is smaller.
Three numbers, three different questions
Total addressable market is the revenue if every possible buyer bought from you: the whole category. Serviceable available market narrows that to the segment your product actually serves, in the geographies you can sell to, at your price point. Serviceable obtainable market is what you can realistically capture in a defined period given your channel, competition and capacity. The gap between the three is where the honest thinking happens, and a deck that shows only TAM is skipping it.
Build it from a countable unit
The strongest version starts with something you can source: the number of registered businesses over a certain size, the number of licensed practitioners, the number of vehicles on the road. Multiply by the proportion that has the problem, then by the proportion you can reach, then by your annual price. Every one of those steps is a number a reader can challenge, and being challengeable is exactly what makes it persuasive.
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Frequently Asked Questions
Should I use top down or bottom up sizing?
Bottom up, always, for the primary number. Top down figures from analyst reports can corroborate it, but a market size built from a countable population and your actual price is the one that survives scrutiny.
What is a realistic SOM?
It depends on your stage and channel, but for an early company one to five percent of SAM within three years is a defensible claim. Anything above ten percent needs a specific reason, such as a locked distribution partnership or a market with only two players.
Should TAM use my price or the market price?
Your price, for a bottom up build. Using an inflated market average makes the number larger and less believable. If your price is expected to change, model both and say so.
Is a small TAM disqualifying?
Not automatically. A narrow market with an urgent problem and no competition can be a better business than a huge one with fifty vendors. What kills a pitch is a TAM that is small and being presented as large.
How do I handle a market I am creating?
Size the adjacent budget it will come out of. If nobody buys your category yet, the money still has to move from somewhere, and naming that budget line is far more convincing than a projected category forecast.
Privacy & Security
Everything runs in your browser; nothing is uploaded.
How to Use
Enter your addressable population, pricing and the filters that narrow it to see TAM, SAM and SOM.
Disclaimer: This tool is provided "as is" without warranty of any kind. Results are for educational and utility purposes.
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