Market Sizing
Estimate TAM, SAM, and SOM with top-down and bottom-up math before you commit build budget or pitch investors.
Overview
Market-sizing is an agent skill most often used in Validate (also Idea) that estimates TAM, SAM, and SOM with top-down and bottom-up approaches for opportunity and pitch prep.
Install
npx skills add https://github.com/phuryn/pm-skills --skill market-sizingWhat is this skill?
- Four-step workflow: market definition, top-down TAM, bottom-up cross-check, then SAM and SOM scoping
- Dual methodology: narrow from industry totals and rebuild from customers × price × frequency
- Explicit growth projections and assumption lists meant for investor or stakeholder review
- Accepts uploaded research and uses web search for current industry and competitor data
- Structured analyst persona for geography, vertical, and customer-type constraints on $ARGUMENTS
- 4 analysis steps: market definition, top-down, bottom-up, SAM scoping
Adoption & trust: 1.1k installs on skills.sh; 12.3k GitHub stars; 2/3 security scanners passed (skills.sh audits).
What problem does it solve?
You have a product idea but no reconciled market size story that investors or your own scope decisions can trust.
Who is it for?
Solo founders preparing investor conversations, choosing a wedge, or comparing market entry options before building.
Skip if: Teams that only need qualitative discovery with no numeric bounds, or markets where you refuse to cite assumptions and external data.
When should I use this skill?
Sizing a market opportunity, estimating addressable market, preparing for investor pitches, or evaluating market entry.
What do I get? / Deliverables
You leave with defined TAM, SAM, and SOM figures, cross-checked methods, stated assumptions, and growth outlook you can fold into validate scope or pricing next steps.
- TAM, SAM, and SOM estimates
- Top-down and bottom-up reconciliation
- Growth projections and key assumptions to validate
Recommended Skills
Journey fit
Spans multiple journey phases - primary shelf plus alternate fits below.
Market sizing is the canonical validate step when you need defensible opportunity numbers tied to scope and entry constraints. Scope subphase is where builders bound the problem, segments, and geography before prototype or pricing decisions harden.
Where it fits
Turn a vague category hunch into bounded TAM slices before you pick a niche to validate.
Decide whether the wedge is large enough to justify an MVP scope doc and timeline.
Connect obtainable market share to revenue ceilings when testing price points.
Reuse SOM logic to set realistic first-year channel targets for a solo launch plan.
How it compares
Structured sizing workflow for agent sessions, not a live data API or spreadsheet template alone.
Common Questions / FAQ
Who is market-sizing for?
Indie and solo builders who need TAM, SAM, and SOM narratives for validation decks, scope gates, or market-entry decisions without hiring an analyst first.
When should I use market-sizing?
Use it in Validate when scoping opportunity; in Idea when research needs numeric bounds; before pricing or prototype when size of prize must justify build; and when preparing investor or partner pitches.
Is market-sizing safe to install?
Review the Security Audits panel on this Prism page before installing; the skill may trigger web search and reads files you provide, so treat uploads and network use like any third-party agent capability.
SKILL.md
READMESKILL.md - Market Sizing
# 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](