Market Sizing — TAM/SAM/SOM Calculator

Calculate defensible TAM, SAM, and SOM market sizes using top-down and bottom-up methods with source citations for pitches and business cases.

Security Scan

This is an instruction-only market-sizing helper whose requirements and instructions match its stated purpose and it does not request credentials, binaries, or install anything.

Purpose & Capability

Name and SKILL.md describe TAM/SAM/SOM calculations and triangulation; the instructions and examples align with that purpose and do not request unrelated capabilities.

Instruction Scope

Instructions are scoped to market-sizing methodology (top-down, bottom-up, triangulation, and citation of public sources). One caution: the bottom-up step mentions counting reachable customers via "databases, directories, LinkedIn," which implies the agent may ask to access external datasets or accounts — the skill itself does not supply credentials or code to do so. If you grant the agent access to private company databases or a LinkedIn session, that would be outside this skill and deserves separate review.

Install Mechanism

No install spec and no code files — instruction-only. Nothing is downloaded or written to disk by the skill itself.

Credentials

The skill declares no environment variables, credentials, or config paths. There are no disproportionate or unexplained secret requests.

Persistence & Privilege

always is false and default autonomy settings apply. The skill does not request persistent system changes or elevated privileges.

Assessment

This is an instruction-only market-sizing skill that appears coherent with its stated purpose. Because it may recommend using external datasets (e.g., directories or LinkedIn), do not grant your agent access to private company databases, personal accounts, or API keys unless you explicitly trust the downstream tool and understand what data will be accessed. Verify all cited sources and assumptions before using numbers in investor materials. Note the README contains promotional links to paid "context packs" — those are external commercial resources, not required for the skill to work.

Build defensible market sizing for any product, pitch deck, or business case. Top-down and bottom-up methodologies combined.

What You Get

• TAM (Total Addressable Market) — entire market if you had 100% share
• SAM (Serviceable Addressable Market) — segment you can actually reach
• SOM (Serviceable Obtainable Market) — realistic capture in 12-36 months
• Bottom-up validation — unit economics × reachable customers
• Source citations — government data, industry reports, public filings

How to Use

Tell me your product/service and target customer. I'll build the full sizing.

Example prompts:

• "Size the market for AI-powered contract review for mid-market law firms in the US"
• "TAM/SAM/SOM for a SaaS helpdesk targeting e-commerce brands doing $1M-$50M revenue"
• "Market size for automated bookkeeping for UK SMBs"

Methodology

Top-Down

1. Start with total industry revenue (cite source)
2. Filter by geography, segment, company size
3. Apply technology adoption rates
4. Result = SAM

Bottom-Up

1. Count reachable customers (databases, directories, LinkedIn)
2. Multiply by realistic ACV (annual contract value)
3. Apply conversion rates at each funnel stage
4. Result = SOM

Triangulation

Compare top-down and bottom-up. If they're within 2-3x of each other, the sizing holds. If wildly different, investigate assumptions.

Output Format

## Market Sizing: [Product/Service]

### TAM — $X.XB
[Total market calculation with sources]

### SAM — $XXM
[Filtered by geography + segment + tech adoption]

### SOM (12-month) — $X.XM
[Bottom-up: customers × ACV × conversion]

### Key Assumptions
- [Assumption 1 + source]
- [Assumption 2 + source]

### Risks to Sizing
- [What could make this smaller]
- [What could make this bigger]

When to Use This

• Pitch decks and investor presentations
• Go-to-market strategy planning
• New product feasibility analysis
• Board presentations and business cases
• Competitive positioning

Pro Tip

Most founders oversize their TAM and undersize their SOM. Investors see through inflated numbers instantly. A tight, well-sourced $50M SAM beats a hand-wavy $10B TAM every time.

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