TAM vs SAM: What's the Difference?

TAM (Total Addressable Market) is the total revenue opportunity if a product captured 100% of every potential customer who could ever use it - the largest possible market figure, with no restrictions for geography, competition, or a specific company's actual ability to reach that customer.

SAM (Serviceable Addressable Market) is the portion of that TAM a specific company can realistically reach given its actual distribution footprint, geographic reach, and business model - a firm can typically only serve markets that are core or directly adjacent to where it already operates.

The two numbers answer different questions, and treating them as interchangeable produces a misleading picture of opportunity. TAM answers "how big could this market theoretically get" - useful for understanding a category's ceiling and for investor conversations about long-term potential, but it says nothing about what any one company can capture given its current reach. SAM answers the more immediate, practical question: given the constraints a company is actually operating under right now, what part of that larger market is genuinely reachable. A company sizing its opportunity using TAM alone risks planning and resourcing around a figure it has no near-term path to reaching, since the gap between TAM and SAM - everything outside a company's current distribution and geographic reach - can represent the majority of the total market.