# Market Sizing Agent Skill > Market sizing with TAM, SAM, and SOM estimates using top-down and bottom-up methods. Get growth projections and key assumptions to validate investor pitches and market entry. - Canonical: https://nanoskill.ai/ja/skills/market-sizing-agent-skill - Markdown: https://nanoskill.ai/ja/skills/market-sizing-agent-skill.md - Author: phuryn - Published: 2026-11-05T09:30:00.000Z - Updated: 2026-11-05T09:40:05.042Z - Language: ja - Source type: github - Popularity signal: 25817 ## Sources - https://github.com/phuryn/pm-skills/tree/main/pm-market-research/skills/market-sizing ## Install ```shell npx skills add https://github.com/phuryn/pm-skills/tree/main/pm-market-research/skills/market-sizing ``` ## About Market sizing helps product managers, founders, and expansion teams quantify a product opportunity before committing resources. It estimates TAM, SAM, and SOM, forecasts growth over two to three years, and surfaces the key assumptions behind each number. The skill combines top-down industry sizing with bottom-up unit economics, reconciles the two approaches, and scopes SAM based on geography, channels, pricing, and product capabilities. It also produces an investor-ready summary table and flags risks with confidence levels. Use it when preparing investor pitches, evaluating a new market entry, or cross-validating estimates with current industry data. Provide a target market and constraints, or share research and competitor data for the skill to analyze directly. ## Key features - **Top-down and bottom-up market sizing**: Triangulate TAM from industry-level data and unit economics, then reconcile both approaches to produce a defensible annual revenue opportunity. - **TAM, SAM, and SOM scoping**: Break the total market into serviceable and obtainable segments with geography, channel, and pricing constraints so you can show a realistic path. - **Growth projections to validate assumptions**: Forecast 2-3 year market evolution and flag high, medium, or low confidence assumptions that may change your estimates. - **Investor-ready market summary**: Generate a concise table comparing current and projected TAM, SAM, and SOM, plus growth drivers and risks for pitch decks. - **Data-backed research and citations**: Use web search and provided reports to ground market sizing in current industry data rather than unsupported numbers. ## Use cases - **Size a new market opportunity**: Product teams use market sizing to quantify demand before committing resources to a new product or feature. - **Prepare an investor pitch**: Founders generate TAM, SAM, and SOM estimates with assumptions to support fundraising narratives. - **Evaluate market entry**: Expansion teams scope geography, customer segments, and serviceable share when entering a new market. - **Cross-validate market estimates**: Analysts compare top-down and bottom-up methods to reconcile market sizing and sharpen forecasts. ## Skill definition # Estimate Market Size (TAM, SAM, SOM) ## Purpose Estimate the Total Addressable Market (TAM), Serviceable Addressable Market (SAM), and Serviceable Obtainable Market (SOM) for a product. Includes both top-down and bottom-up estimation approaches, growth projections, and key assumptions to validate. ## Instructions You are a strategic market analyst specializing in market sizing, opportunity assessment, and growth forecasting. ### Input Your task is to estimate the market size for **$ARGUMENTS** within the specified market constraints (geography, industry vertical, customer type, etc.). If the user provides market research, industry reports, financial data, or competitor information, read and analyze them directly. Use web search to find current market data, industry reports, and growth projections. ### Analysis Steps (Think Step by Step) 1. **Market Definition**: Define the market boundaries — what problem space, which customer segments, what geography or constraints apply 2. **Top-Down Estimation**: Start from total industry size and narrow to the relevant slice 3. **Bottom-Up Estimation**: Build from unit economics (customers × price × frequency) to cross-validate 4. **SAM Scoping**: Identify which portion of TAM is realistically serviceable given product capabilities, channels, and constraints 5. **SOM Estimation**: Estimate achievable share in the next 1-3 years based on competitive position and go-to-market capacity 6. **Growth Projection**: Forecast how TAM, SAM, and SOM may evolve over the next 2-3 years 7. **Assumption Mapping**: Surface the key assumptions underlying each estimate ### Output Structure **Market Definition** - Problem space and customer need - Geographic and segment boundaries - Key constraints or scoping decisions **TAM (Total Addressable Market)** - Top-down estimate with sources and reasoning - Bottom-up estimate for cross-validation - Reconciliation of the two approaches - Current TAM value (annual revenue opportunity) **SAM (Serviceable Addressable Market)** - Which portion of TAM the product can realistically serve - Constraints: geography, language, channels, product capabilities, pricing tier - SAM as percentage of TAM with reasoning **SOM (Serviceable Obtainable Market)** - Realistic share achievable in 1-3 years - Basis: competitive position, go-to-market capacity, current traction - SOM as percentage of SAM with reasoning **Market Summary Table** | Metric | Current Estimate | 2-3 Year Projection | |--------|-----------------|---------------------| | TAM | | | | SAM | | | | SOM | | | **Growth Drivers & Trends** - Key factors that could expand or contract the market - Technology, regulatory, demographic, or behavioral shifts - Emerging segments or adjacent markets **Key Assumptions & Risks** - Critical assumptions behind each estimate (numbered) - Confidence level for each (high / medium / low) - How to validate the most uncertain assumptions - What would materially change the estimates ## Best Practices - Always provide both top-down and bottom-up estimates to triangulate - Use web search for current industry data, analyst reports, and market benchmarks - Cite sources for market data — avoid unsupported numbers - Be explicit about assumptions; label estimates vs. data - Distinguish between value-based (revenue) and volume-based (users/units) sizing - Consider currency and purchasing power parity for international markets - Flag where estimates have wide confidence intervals - Recommend specific data sources or research to sharpen estimates --- ### Further Reading - [Market Research: Advanced Techniques](https://www.productcompass.pm/p/market-research-advanced-techniques) - [User Interviews: The Ultimate Guide to Research Interviews](https://www.productcompass.pm/p/interviewing-customers-the-ultimate) - [Crossing the Chasm: The Ultimate Guide For PMs](https://www.productcompass.pm/p/crossing-the-chasm) - [Product Innovation Masterclass](https://www.productcompass.pm/p/product-innovation-masterclass) (video course) ## FAQ ### What is TAM, SAM, and SOM in market sizing? TAM is total addressable market, SAM is serviceable addressable market, and SOM is serviceable obtainable market. This skill estimates all three using top-down and bottom-up approaches. ### How does the market sizing skill work? You provide a target market and constraints. It defines market boundaries, runs top-down and bottom-up estimates, scopes SAM and SOM, and projects growth over 2-3 years. ### What is the difference between top-down and bottom-up market sizing? Top-down starts from total industry size and narrows to the relevant slice; bottom-up builds from unit economics like customers, price, and frequency. The skill uses both to cross-validate. ### Can it help me prepare an investor pitch? Yes. The output includes a summary table with current and projected TAM, SAM, and SOM, plus growth drivers, assumptions, and risks suitable for pitch materials. ### Does it provide growth projections? Yes. It forecasts TAM, SAM, and SOM over the next 2-3 years and lists growth drivers, emerging segments, and risks that could change estimates. ### How do I use the skill for a specific market? Provide your target market and constraints such as geography, industry vertical, or customer type. You can also share market research and competitor information for the skill to analyze directly.