Serviceable Obtainable Market (SOM)

SOM is the most realistic of the three market-size estimates. Total addressable market shows the full opportunity, serviceable available market shows what the company's offering could serve, and SOM estimates what the company can actually win.

For example, if a company's serviceable available market is 200,000,000 a year, it might estimate that it can capture about 10% within five years, given strong competitors and its sales capacity, giving a SOM of 20,000,000.

SOM is often estimated by considering the company's current market share, sales team size, marketing budget, growth rates of similar companies and the strength of competitors.

Start-ups commonly present TAM, SAM and SOM in investor pitches. Investors tend to be sceptical of very large TAM figures and pay closer attention to whether SOM estimates are credible and supported by evidence such as early sales, customer interest and realistic growth plans.