TAM Validation Bottom Up

Use This Skill When

• The user wants to test whether a management TAM claim is credible.
• A growth thesis relies on a very large addressable market that may be inflated.
• Top-down industry numbers are too broad, double-counted, or detached from actual buyer behavior.
• The key question is not "how big is the market" but "how much monetizable spend is realistically reachable."

Required Inputs

• Product being sold, target buyer, use case, and monetization model.
• Management TAM claim and the stated methodology, if available.
• Bottom-up unit drivers such as number of customers, seats, locations, devices, transactions, or workloads.
• Pricing or annual spend assumptions by customer type.
• Adoption constraints such as budget, regulation, deployment friction, replacement cycles, and competitive intensity.
• Optional but useful: peer penetration, category analogues, and international vs domestic differences.

Workflow

1. Define the market boundary. Be explicit about product scope, buyer type, geography, and whether the company sells point solutions or broader platform spend.
2. Rebuild TAM from first principles. Estimate reachable units multiplied by realistic spend, then separate current core use cases from aspirational adjacency.
3. Apply constraint analysis. Reduce the raw opportunity for adoption friction, budget authority, replacement cadence, incumbency, and product fit.
4. Cross-check against analogues. Compare implied penetration and spend assumptions to adjacent software categories or earlier category winners.
5. Produce a credible range. Present base, upside, and downside TAM ranges with the key sensitivity variables.
6. Translate to the thesis. Explain whether the company needs heroic assumptions to support the current valuation.

Output Requirements

• Show the difference between theoretical TAM, serviceable market, and realistically monetizable market.
• Make assumptions explicit enough that another analyst could challenge them.
• Identify exactly where management's TAM framing is too broad or too optimistic.
• End with the one or two assumptions that matter most for the conclusion.
• Keep the answer grounded in buyer behavior, not vendor narrative.

Output Template

Quality Checks

• TAM is built from actual units and spend, not repeated top-down market reports.
• Core market and adjacency are clearly separated.
• Spend assumptions match the buyer and budget owner being analyzed.
• Constraints reduce the raw opportunity instead of being mentioned as an afterthought.
• The conclusion says whether TAM is investable, inflated, or still uncertain.

Guardrails

• Do not accept management's TAM slide without reconstructing it.
• Do not double-count overlapping spend pools or adjacent categories.
• Do not assume 100% adoption of theoretically addressable users.
• Avoid using a global market number when the go-to-market motion is geographically narrow.
• If price per customer is unstable, present a range rather than false precision.

Example Prompts

• Validate this company's TAM claim from the bottom up and tell me if it is realistic.
• Rebuild the addressable market using customers, spend, and adoption constraints instead of management slides.
• Show me whether the current valuation depends on an inflated TAM assumption.