All termsPRODUCT & MARKET

TAM / SAM / SOM

Also known as: Total Addressable Market · Serviceable Addressable Market · Serviceable Obtainable Market

DEFINITION

Three nested measures of market size — the total market opportunity (TAM), the portion you can realistically serve (SAM), and the slice you can capture near-term (SOM).

In depth

TAM = everyone who could ever buy this kind of product globally. SAM = the subset your product actually reaches (geography, language, segment). SOM = the share you can realistically capture in the next 3–5 years given team, capital, competition.

Investors quickly discount founder TAMs because everyone inflates them. The credible pitch leads with SOM ("we can do $50M ARR in 5 years") backed by SAM math ("there are 200K mid-market SaaS companies globally, typical ACV $12K").

Formula & example

EXAMPLEA US-only SMB HR SaaS: TAM = global HR software ~$30B. SAM = US SMB HR ~$4B. SOM = 1% capture in 5 years = $40M ARR.

Rules of thumb

  • TAM over $1B is the usual minimum to attract VC.
  • SOM should be defensible with real conversion + channel math.
  • Prefer bottom-up TAM (customers × price) over top-down (percent of industry report).

Put it into practice

tool
Market Size Calculator

Related terms

PMF
The state where a product satisfies a real market demand so well that customers adopt, pay, and stay without heroic growth effort.

USE THIS IN A REAL PLAN

Turn concepts into a real SaaS blueprint

PlanMySaaS runs TAM / SAM / SOM and every other SaaS metric for your idea — part of a full blueprint with architecture, feature specs, 21 docs, and Cursor-ready prompts.

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Last reviewed 14 April 2026 by Abhi Verma.