TAM Prompt Builder

Estimate the size of the opportunity before you build.

Total Addressable Market (TAM) is a way of asking, "How big could this be if everything went right?" A top-down TAM starts with a broad spending pool, such as "$12B in annual heart failure spending," then estimates what portion could relate to the solution. For clinicians, the useful version is usually more bottom-up: how many patients, clinicians, hospitals, practices, or payers might actually need the solution, what they could pay, and what portion you could realistically reach.

Use this page to generate a prompt for your preferred LLM. The prompt asks for TAM, SAM, and SOM in plain language, with conservative, base-case, and aggressive estimates, explicit assumptions, reimbursement codes when relevant, and cited sources.

How to interpret the LLM output

TAM is not the same thing as a startup opportunity.

TAMTotal possible market

SAMReachable market

SOMRealistic early share

TAM is the broad universe that could theoretically use the solution. SAM (3-5 years) is the reachable portion given your geography, segment, workflow, regulation, and business model. SOM (1-2 years) is the share you might realistically win first with your evidence, team, distribution, and budget constraints.

Use SAM as a rough fundability signal. A SAM above about $100M in annual market size is on the order of venture scale, because it can plausibly support a large outcome if the company wins a meaningful share. Smaller SAMs can still support strong businesses, but they may fit better with bootstrapping, grants, strategic partnerships, services, or acquisition-led paths than a traditional venture capital model. Market size alone does not make a company fundable; investors also look for urgency, evidence, margins, distribution, defensibility, and a credible path to exit.

Build the prompt

Give the LLM enough context to reason from the bottom up.

Fill in what you know. Leave unknowns blank; the generated prompt will ask the LLM to state assumptions instead of pretending certainty.

Generated prompt updates as you type.

Your preferred LLMThe prompt works best with a model that can browse or cite sources. SolutionDescribe the product or service in plain clinical language. Problem it solvesState the painful workflow, patient-care, cost, or quality problem. Primary user and buyerSeparate the person using the tool from the person or organization paying for it. Market segmentsInclude care settings, customer types, patient groups, or geographies. GeographyMarkets differ by reimbursement, workflow, regulation, and sales motion. Pricing hypothesisIf unknown, say unknown. The prompt will ask for plausible pricing ranges. Reimbursement codes, if applicableInclude codes only if they might apply; otherwise note likely budget owner. Known competitors or substitutesSubstitutes matter even when there is no direct competitor. Other contextAdd anything that should shape the assumptions.