Master TAM/SAM/SOM calculations, market sizing methodologies, and validation frameworks...
Frameworks and methodologies for estimating market size and validating market opportunity.
Market sizing answers the critical question: "Is this opportunity large enough to pursue?" It provides the foundation for strategic decisions, resource allocation, and investment prioritization.
Core Principle: Market sizing is educated guessing with documented assumptions. The goal is reasonable estimates and order-of-magnitude accuracy (is it $1M, $10M, or $100M?), not false precision.
Key Insight: Always use multiple methods (bottom-up, top-down, value theory) to triangulate and validate estimates. If methods disagree by more than 2-3x, your assumptions need scrutiny.
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market-analyst - For TAM/SAM/SOM calculation and market validationUse when you need to:
Definition: Total revenue opportunity if you achieved 100% market share globally.
Purpose: Understand the absolute ceiling of opportunity.
Typical Range:
Calculation: See three methods below.
Definition: Portion of TAM you can realistically serve given your business model, geography, and product capabilities.
Purpose: Your realistic target market after applying real-world constraints.
Filters to Apply:
Typical Range: SAM is usually 10-40% of TAM for focused products.
Formula:
SAM = TAM × Geographic % × Segment % × Product Fit % × Distribution %
Definition: Portion of SAM you can realistically capture in the near term (1-3 years).
Purpose: Your achievable revenue target given resources, competition, and time constraints.
Realistic Benchmarks:
Formula:
SOM = SAM × Realistic Market Share %
Reality Check: Convert SOM to customer count. Is that number achievable per month/week?
Always use all three methods for robust validation. If they disagree significantly, investigate your assumptions.
Approach: Count actual customers and multiply by revenue per customer.
Formula:
TAM = Total Potential Customers × Average Revenue per Customer
Process:
Strengths:
When to Use: Always start here as your primary method.
Complete methodology: See references/market-sizing-methodologies.md for detailed step-by-step process with examples.
Approach: Start with total market size and estimate your segment percentage.
Formula:
TAM = Total Market Size × Your Segment %
Process:
Strengths:
Weaknesses:
When to Use: As secondary validation, never as primary method.
Complete methodology: See references/market-sizing-methodologies.md for examples and industry applications.
Approach: Calculate value created for customers, then estimate capture rate.
Formula:
TAM = (Value Created per Customer × Potential Customers) × Capture Rate %
Process:
Strengths:
When to Use: To validate pricing is reasonable relative to value created.
Complete methodology: See references/market-sizing-methodologies.md for value calculation frameworks.
Before trusting your market sizing, validate with these critical tests:
1. Can you name 10 specific potential customers?
2. Are there existing competitors making money?
3. Does TAM > SAM > SOM make sense?
4. Is Year 1 SOM achievable with your resources?
5. Is the market big enough to justify effort?
Complete validation checklist: See assets/market-validation-checklist.md for comprehensive 100+ point validation framework.
Detailed guide: See references/market-sizing-best-practices.md for:
Use this as your primary estimate:
Tool: Use assets/market-sizing-calculator.md for step-by-step worksheet with formulas.
Validate your bottom-up with industry data:
Test pricing reasonableness:
Narrow TAM to realistic serviceable market:
Starting TAM: $__________
Geographic filter: × ____% = $__________
Segment filter: × ____% = $__________
Product fit filter: × ____% = $__________
Distribution filter: × ____% = $__________
Final SAM: $__________
Template: Use assets/tam-sam-som-template.md for complete calculation template.
Project achievable market capture:
Conservative Approach:
Consider:
Run through comprehensive validation:
Validation tool: Use assets/market-validation-checklist.md for systematic validation.
Critical for updating as you learn:
## Key Assumptions
1. Customer count: [number]
- Source: [where this came from]
- Confidence: [High/Medium/Low]
- Impact if wrong: [+/- X% on TAM]
2. Pricing: $[amount]/year
- Basis: [competitive analysis, value-based, etc.]
- Confidence: [High/Medium/Low]
- Impact if wrong: [direct 1:1 impact]
3. Adoption rate: [%]
- Basis: [customer interviews, analogies, etc.]
- Confidence: [High/Medium/Low]
- Impact if wrong: [+/- X% on TAM]
Complete TAM/SAM/SOM Template:
assets/tam-sam-som-template.mdStep-by-Step Calculator:
assets/market-sizing-calculator.mdValidation Checklist:
assets/market-validation-checklist.mdComplete Methods Guide:
references/market-sizing-methodologies.mdBest Practices Guide:
references/market-sizing-best-practices.mdMarket sizing is educated guessing - the goal is reasonable estimates with documented assumptions, not precision.
The Three-Step Approach:
Key Principles:
Decision Framework:
"My TAM and bottom-up numbers disagree by 10x": This is common. Bottom-up is almost always more realistic. If the gap is huge, your TAM assumptions are too broad. Narrow your market definition or segment further.
"I can't find reliable data for my niche": Use proxies. Find adjacent markets with data, then estimate your slice. Combine multiple weak signals rather than relying on one perfect source. Note your assumptions explicitly.
"My SOM looks embarrassingly small": That's probably accurate for year 1. A realistic SOM of $200K is more credible than a fantasy SOM of $10M. Investors prefer honest sizing with a clear expansion path.
product-positioning - Position against competitive landscapeproduct-market-fit - Validate market demand existscompetitive-analysis-templates - Analyze market attractiveness and competitive dynamics