TAM, SAM and SOM

Total addressable market (TAM) counts every company that has the problem your category solves. Serviceable addressable market (SAM) keeps only those you can actually serve: the countries you sell into, the languages you support, the integrations you have, the sizes your pricing fits. Serviceable obtainable market (SOM) is the slice of SAM you can expect to win in a given period with your current team and budget.

For outbound, the useful number is usually the count of accounts in your SAM that match your ICP, because that is the list you will research and contact. Counting it bottom-up, account by account, is more honest than multiplying an industry report's revenue figure by a percentage. A SAM that is too small for your sending plan is an early sign to widen the ICP or add a second segment before you run out of good accounts.