Total addressable market is the total revenue available if every company that could buy your offer did. Serviceable addressable market narrows it to the companies you can actually reach and serve. Serviceable obtainable market is the share you can realistically win in a period. Only the last two change what you do on Monday.
What it is
Three nested numbers answering three different questions. TAM: how many organizations exist that have this problem at all. SAM: how many of them fall inside the geography, language, size and category you can serve. SOM: how many you can realistically win given your capacity, price and competition. A TAM quoted alone is a slide. A SAM you can list company by company is a plan, and it is the only one of the three you can verify.
How it works
Two methods, and the disagreement between them is the useful output. Top down starts from an industry total and applies a share, which is fast and inherits every error in the published figure. Bottom up counts real companies in a countable segment and multiplies by an average deal value you have actually charged. When the two land far apart, the assumption to inspect is usually the one you did not write down: an average price nobody pays, or a category that includes companies you cannot serve.
Why it matters for winning clients
Market sizing decides where a small team spends the only week it has. It answers whether a niche can support the business at your price, whether to widen the category or the geography when a segment stalls, and what to say to a client who asks how many potential customers their own market holds. Done bottom up it also produces a byproduct worth more than the estimate: a list of the actual companies.
Example in LeadCanvas
An agency sizes its market from countable inputs rather than industry reports. Our own July 2026 study covered 231,349 deduplicated business listings across 403 cities and 37 sectors, and that structure is what makes a bottom up count possible: category by category, city by city. The team multiplies the companies returned for its category and cities by its own average retainer, then applies its real close rate to get an obtainable number instead of an aspirational one.
Common mistakes
Reporting TAM as if it were pipeline. Using an average deal value from your best client rather than your median one. Counting companies you cannot legally, linguistically or logistically serve. And treating the number as static, when a new service line or a new city changes SAM immediately and TAM not at all.
Related terms
Firmographic data supplies the fields a bottom up count filters on. The ideal customer profile defines the boundary between TAM and SAM. List building turns the count into companies you can contact. The links below open the calculator and the search tool.