Stage 3 · Pitch and close

TAM, SAM, SOM Calculator (Bottom-Up)

Size your market from real customers and prices, segment by segment, with built-in sanity checks.

Free, no sign-up. Your numbers stay in your browser.

Please note. This tool is for education and planning. It gives estimates, not financial advice. Results are estimates based on what you enter. Full disclaimer · How we build the numbers

What this tool does

Bottom-up market sizing counts real customers and what they pay. TAM is everyone who could buy, SAM is the part you can actually serve, and SOM is what you can realistically win in a few years.

How to use it

List the segments you sell to, with the number of organisations in each.
Estimate the share that fits your product today and the annual price.
Set the share of SAM you can win by year 5.

The maths, in plain view

TAM = Σ organisations × annual price
SAM = Σ organisations × fit % × annual price
SOM = SAM × share you can win

A worked example

250k software teams, 120k e-commerce brands and 60k agencies give a TAM of about $1.9B. With fit rates of 25-40%, SAM is about $0.7B; winning 3% of it by year 5 is a SOM of about $20M.

Tips

Name the source of every organisation count.
Investors trust a smaller, well-built SAM more than a giant top-down TAM.

Questions people ask

What is the difference between TAM, SAM and SOM?

TAM is the total demand for your type of product. SAM is the part you can serve with your product, geography and channels. SOM is the share of SAM you can realistically capture in the next few years.

Top-down or bottom-up market sizing?

Investors prefer bottom-up: number of customers × price. Use a top-down number from a published report only as a cross-check.

How big should a SAM be for VCs?

Large enough for a venture-scale outcome. Many investors want to see a path to $100M+ in revenue, so the SAM usually needs to be at least several hundred million dollars.

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