Total Addressable Market (TAM)
ICP & Targeting- Definition
- Total Addressable Market (TAM) is the top-down estimate of annual revenue your product could generate if it achieved 100% market share in a defined segment. TAM is typically calculated by multiplying the number of potential accounts in your ICP by the average ACV. It sets the ceiling for your growth narrative — investors care about TAM as a proxy for headroom — but it is not a near-term pipeline metric. SAM (Serviceable Available Market) and SOM (Serviceable Obtainable Market) are the nearer-term slices.
Why it matters
TAM is the single number that frames every growth decision. Too small and investors pass; too broad and your strategy lacks focus. A well-scoped TAM accounts for your actual ICP, not the entire software industry. It is a directional number, not a target.
Example
A company selling conference data to US B2B SaaS companies with outbound teams calculates TAM: 5,000 ICP-qualified accounts × $12,000 ACV = $60M TAM. But they only have outbound capacity to reach 500 accounts this year — that's the SOM slice, and it tells them whether their current pipeline supports the number.
How Impossible Data helps
Conference attendee datasets help you size your TAM by revealing exactly how many ICP-matching accounts attend the events your buyers care about each year.