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TAM / SAM / SOM Calculator

Calculate Total, Serviceable, and Obtainable market with both bottom-up and top-down methods. The exact framing investors expect on slide 5 of your deck.
TAM
Total Addressable Market
$6.00B
100% of TAM
SAM
Serviceable Addressable Market
$1.50B
25% of TAM
SOM
Serviceable Obtainable Market
$75.0M
1% of TAM

What is the tam / sam / som calculator?

TAM (Total Addressable Market) is the total annual revenue available if every potential customer in the world bought your product. SAM (Serviceable Addressable Market) is the slice of TAM your product, geography, and channels can actually reach. SOM (Serviceable Obtainable Market) is the realistic share of SAM you can capture in the next 3–5 years.

This calculator supports both methods: bottom-up (multiply potential customers × annual contract value) and top-down (start with an analyst report and segment down). Investors strongly prefer bottom-up.

Why this matters for founders & operators

Market size determines whether your business can become big enough to justify venture-scale returns. Investors who write Series A checks generally need to see at least a $1B+ TAM with a credible path to a $100M+ SOM.

But the actual goal isn't a giant TAM — it's a credible, defensible calculation. A $50B TAM with a hand-wavy methodology is worse than a $5B TAM with bottom-up math. Most experienced investors mentally discount the TAM number and look at SAM and SOM instead.

Get this right early: bad market sizing on slide 5 is one of the fastest ways to lose investor confidence in the rest of your deck.

How to use this calculator

  1. 1
    Pick the bottom-up method

    Multiply the number of potential customers × what each would pay you per year. This is the method most investors trust because it forces you to defend each number.

  2. 2
    Estimate total reachable customers honestly

    Globally, in your category. Resist the urge to inflate this. If you serve dentists in the US, the number is ~200K — not '10M small businesses.'

  3. 3
    Set a realistic annual price

    Use your actual ACV today, or your stated future ACV if you have a clear pricing roadmap. Don't use list prices that nobody pays.

  4. 4
    Define SAM by what you can actually reach

    Filter for: geographies you can sell into, segments your product serves, channels you can deploy. SAM is typically 10–40% of TAM for early-stage companies.

  5. 5
    Set SOM as a realistic 3–5 year capture

    Based on your sales motion, capacity, and competition. 1–10% of SAM is normal for ambitious-but-credible plans.

FAQ

Which is better, top-down or bottom-up market sizing?+
Bottom-up. Top-down (e.g., '0.5% of a $50B market') is what investors call a 'sniff test' answer — it tells them you didn't do the work. Bottom-up forces you to think about who your customer is and what they'd pay.
Do I need to show all three on my pitch deck?+
Yes. Investors expect TAM (vision), SAM (where you'll play), SOM (realistic 3–5yr capture). Showing only TAM looks naive; showing only SOM looks unambitious.
What if my market is genuinely new (no analyst data)?+
Use bottom-up exclusively. Build a customer count from public sources (BLS, Census, LinkedIn searches) and a price from comparable products. Comp price-points if pricing is unclear.
How big should TAM be for a Series A?+
Conventional wisdom: $1B+ TAM with a believable path to $100M+ revenue in 5–7 years. Smaller markets can work for vertical SaaS but expect harder questions on expansion potential.
Should TAM include only software revenue or my full pricing model?+
Whatever you actually sell. If you sell software and services bundled, include both. If you charge a take-rate, calculate gross transaction value × take-rate.