What is TAM, SAM, SOM?
TAM, SAM, and SOM are nested measures of market size used to size an opportunity. TAM (Total Addressable Market) is the total revenue available if you captured 100% of the market. SAM (Serviceable Addressable Market) narrows that to the segment your product and business model can actually serve. SOM (Serviceable Obtainable Market) is the realistic share you can capture in the near term given competition and reach.
These estimates matter for prioritization, fundraising, and strategy — they help teams decide whether an opportunity is big enough to pursue and set credible growth expectations. They can be estimated top-down (from industry reports) or bottom-up (from realistic customer counts and pricing), with bottom-up usually more defensible.
PMs use market sizing to justify investment in a new product or segment and to compare opportunities. Inflated TAM figures are a classic red flag; the SOM is usually the most decision-relevant number.
Examples
- A new feature's TAM is all SMBs, SAM is English-speaking SMBs in 3 verticals, SOM is the 2% reachable in year one.
- A PM builds a bottom-up SOM estimate to justify investment in a new market segment.
Where PMs use this
Related terms
Product-Market Fit
The point at which a product satisfies strong market demand — the prerequisite for scalable growth.
Go-to-Market (GTM)
The plan for how a product reaches its target customers — positioning, pricing, channels, and launch.
Value Proposition
A clear statement of the unique benefit a product delivers to a specific customer and why it beats alternatives.