Market Sizing (TAM / SAM / SOM)

Summary

TAM is the total addressable market, SAM is the segment you can realistically serve, and SOM is what you can realistically capture — used to sanity-check whether an opportunity is worth pursuing.

• 1Estimate TAM/SAM/SOM for a product idea using a top-down and a bottom-up approach.
• 2Compare your two estimates — big gaps usually mean a flawed assumption somewhere.
• 3Practice this out loud — it's a very common interview exercise (see Phase 15).