The total revenue available if a product or service captured every possible customer for it. The biggest number in the deck, which is why it deserves the most suspicion.
No metric is inflated more cheerfully than TAM, because no metric is further from ever being tested. Nobody is held to a market size the way they are held to a forecast.
Last reviewed 3 July 2026 · Free and ungated
Selected senior operators who have entered markets, and left them, can test the sizing before capital follows it.
Challenge the assumptions before committingTotal addressable market is the annual revenue opportunity if an offering achieved 100 per cent share of everyone who could conceivably use it. It is usually quoted alongside SAM, the serviceable addressable market you can actually reach with your model and geography, and SOM, the share of that you might realistically obtain. Each step down is smaller and more honest.
TAM answers exactly one question: is this market big enough to bother with? It sets an upper bound, and it says nothing about whether customers will switch, what acquiring them costs, or who else is competing for the same spend. Market entry and investment decisions turn on SOM and the path to it. A pitch that spends its energy on TAM and a single slide on the path is describing the ocean to avoid discussing the boat.