Total Addressable Market

Total addressable market (TAM) is an estimate of the total annual revenue available if a product captured every possible customer in its market. It is the widest of three nested figures: TAM covers the whole market, serviceable addressable market (SAM) narrows to the portion the company's business model and geography can actually reach, and serviceable obtainable market (SOM) estimates the share realistically winnable in the near term. Founders present the three together in fundraising materials to show that a market is large enough to support a venture-scale outcome. Two methods are common. Top-down starts from published industry research and applies a percentage, which is fast but easy to inflate. Bottom-up multiplies the number of potential customers by a realistic annual contract value, which is harder to produce and far more credible because each assumption can be checked. Investors generally discount top-down numbers on sight. The frequent mistake is defining the market so broadly that the figure loses meaning, such as claiming the entire software market for a narrow tool. Estimates for emerging categories such as generative AI vary widely between research firms, so a specific bottom-up calculation with stated assumptions carries more weight than a large headline number.