What Is Total Addressable Market?
TL;DR
Total addressable market, or TAM, is the total annual revenue available if every company that could buy your product did. In outbound it is calculated bottom up: count the accounts matching your ideal customer profile, then multiply that count by what one account is worth per year.
How do you calculate total addressable market?
Bottom up, from a count you can defend. Enter your ideal customer profile as filters on a contact database, read the number of matching accounts, and multiply by your average annual contract value. Both inputs come from your own data, which is what makes the result arguable rather than asserted.
The top-down alternative starts from a published market size and takes a share of it. It is faster and much weaker, because the published figure was scoped by someone else for another purpose, so the segment it covers rarely matches the one you sell into.
How do TAM, SAM and SOM differ?
They are three nested circles. TAM is every account that could buy. SAM, the serviceable addressable market, is the part of TAM you can actually sell to today given your geography, language, pricing and product limits. SOM, the serviceable obtainable market, is the share of SAM you can realistically win in a planning period given your capacity.
SAM is the one that matters for an outbound plan. TAM is a strategic number that answers whether the market is big enough to build in, while SAM is the list you can build this quarter, so confusing them produces a target nobody can work.
Why does TAM matter for an outbound list?
Because it tells you whether your problem is coverage or conversion. A serviceable market of a few thousand accounts means you can contact all of them, so any shortfall is about the message and the targeting inside the list rather than the size of it. Buying more records will not help.
A serviceable market of hundreds of thousands means the opposite: you will only ever touch a fraction, so prioritisation and segmentation are where the leverage sits. Running the count before buying is what tells you which of the two situations you are in.
Frequently asked questions
Bottom up whenever you can count accounts, which in B2B you almost always can. A top-down estimate inherits the scope of whatever report it came from, so it cannot be checked and cannot be turned into a list. A bottom-up count can be audited filter by filter.