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StrategyM

Market Sizing (TAM / SAM / SOM)

Definition

Three nested lenses for estimating market opportunity. Total Addressable Market (TAM) is the total demand for a product or service if 100% market share were captured. Serviceable Addressable Market (SAM) is the segment the company can realistically target. Serviceable Obtainable Market (SOM) is the share the company can capture in the near term. PMs use market sizing to evaluate new product opportunities, justify investment, and communicate potential to stakeholders.

Why It Matters for Product Managers

Understanding market sizing is critical for product managers because it directly influences how teams prioritize work, measure progress, and deliver value to users. PMs use market sizing to evaluate new product opportunities, justify investment, and communicate potential to stakeholders. Without a clear grasp of this concept, PMs risk making decisions based on assumptions rather than evidence, which can lead to wasted engineering effort and missed market opportunities.

How It Works in Practice

Product leaders apply this strategic concept through a series of deliberate steps:

  • Assess — Evaluate the current competitive landscape, market dynamics, and internal capabilities that shape the opportunity.
  • Define — Articulate a clear position or strategic choice that differentiates the product and guides prioritization.
  • Communicate — Share the strategic direction with every team and stakeholder so decisions across the organization stay aligned.
  • Measure — Track leading indicators that signal whether the strategy is working, and be prepared to adapt when evidence suggests a course correction.

    • Market sizing is not a one-time exercise. The strongest product teams revisit strategic concepts regularly as new data and competitive moves reshape the landscape.

    Common Pitfalls

  • Confusing strategy with tactics — defining what to build without first articulating why it matters.
  • Setting the strategy once and never revisiting it as the market and competitive landscape evolve.
  • Failing to communicate the strategy clearly enough for every team member to make aligned decisions.

    • Related Concepts

    To build a more complete picture, explore these related concepts: Blue Ocean Strategy, and Positioning. Each connects to this term and together they form a toolkit that product managers draw on daily.

    Related Terms

    Go-to-Market Strategy (GTM)Blue Ocean StrategyPositioning

    Frequently Asked Questions

    What is market sizing in product management?+
    Three nested lenses for estimating market opportunity. Product managers use this concept to make more informed decisions and deliver better outcomes for users and the business.
    Why is market sizing important for product strategy?+
    Market Sizing is important because it helps product teams differentiate in competitive markets, allocate resources effectively, and build sustainable advantages. Without strategic thinking, teams risk building features that fail to compound into lasting value.
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