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market-sizing-analysis

market sizingTAMSAMSOMstartupbusiness strategyfundraisingmarket analysis
36.8k📄 MIT🕒 2026-06-16Source ↗

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Works across Claude Code, Cursor, Codex, Copilot & Antigravity

Market Sizing Analysis provides a structured approach for estimating the financial viability of a business opportunity. This skill breaks down market potential into three distinct layers: the total universe (TAM), the segment your product can actually reach (SAM), and the portion you can realistically capture within five years (SOM). By applying different analytical models—top-down industry assessments, bottom-up customer counts, or value-based pricing logic—you can move past speculative projections toward evidence-based business planning. This skill assists founders, product managers, and investors in clarifying the scale of a problem, justifying pricing strategies, and setting growth expectations. It transforms ambiguous market intuition into quantitative data points suitable for pitch decks, roadmap prioritization, and strategic planning without relying on guesswork or vanity metrics.

When to Use This Skill

  • Building financial projections for investor pitch decks or seed funding
  • Deciding whether to enter a new geographic region or customer demographic
  • Setting realistic 3-year revenue targets for new product lines
  • Evaluating the potential ROI of disruptive innovations in crowded industries

How to Invoke This Skill

Example prompts that trigger this skill in Claude Code, Cursor, or Antigravity:

  • Calculate the TAM for my new SaaS product
  • Perform a bottom-up market sizing analysis for the North American e-commerce sector
  • Estimate the serviceably obtainable market for our AI tool
  • Help me determine our market size based on value theory
  • Analyze the growth potential of this niche market

Pro Tips

  • 💡Always combine at least two methodologies (e.g., top-down and bottom-up) to cross-validate your market sizing results and improve accuracy.
  • 💡When defining SAM, be realistic about your initial target segments and geographic reach. Overestimating can lead to flawed strategy.
  • 💡Clearly articulate your assumptions when presenting market sizes, as these are critical for stakeholders to understand the basis of your calculations.

What this skill does

  • Calculates TAM, SAM, and SOM using three distinct quantitative methodologies
  • Translates industry-wide report data into specific addressable service markets
  • Models market potential based on bottom-up customer segment aggregation
  • Determines pricing thresholds using value-based willingness-to-pay calculations
  • Validates strategic viability for new product launches or geographic expansion

When not to use it

  • When you lack even basic data on customer counts or competitor pricing
  • When performing short-term tactical marketing or lead generation tasks

Example workflow

  1. Define the specific problem, target geography, and customer segment
  2. Select the appropriate methodology based on data availability
  3. Gather external industry statistics or internal customer unit economics
  4. Apply the formulas to derive TAM, SAM, and SOM figures
  5. Adjust results based on realistic competitive capture rates

Prerequisites

  • Clearly defined product or service category
  • Target customer profile
  • Basic industry revenue or user data

Pitfalls & limitations

  • !Over-relying on top-down reports that exclude your specific niche
  • !Selecting overly optimistic penetration rates that lack competitive justification
  • !Confusing the total global market with what you can actually reach

FAQ

What is the difference between TAM, SAM, and SOM?
TAM is the entire market universe, SAM is the portion you can target with your specific offering, and SOM is the realistic share you expect to capture in the near term.
Which methodology should I use for a brand new product?
Value theory is typically best for new categories where no historical data exists, as it focuses on the cost of the problem being solved.
How do I avoid overestimating my market size?
Ensure your SAM is heavily filtered by your actual constraints and apply conservative capture rates (usually 2-5%) to your SOM.

How it compares

Unlike generic spreadsheet estimations, this skill forces a choice between three rigorous frameworks, preventing the common mistake of blindly inflating TAM figures.

Source & trust

37k stars📄 MIT🕒 Updated 2026-06-16
📄 Full skill instructions — original source: wshobson/agents
# Market Sizing Analysis

Comprehensive market sizing methodologies for calculating Total Addressable Market (TAM), Serviceable Available Market (SAM), and Serviceable Obtainable Market (SOM) for startup opportunities.

## Overview

Market sizing provides the foundation for startup strategy, fundraising, and business planning. Calculate market opportunity using three complementary methodologies: top-down (industry reports), bottom-up (customer segment calculations), and value theory (willingness to pay).

## Core Concepts

### The Three-Tier Market Framework

**TAM (Total Addressable Market)**

- Total revenue opportunity if achieving 100% market share
- Defines the universe of potential customers
- Used for long-term vision and market validation
- Example: All email marketing software revenue globally

**SAM (Serviceable Available Market)**

- Portion of TAM targetable with current product/service
- Accounts for geographic, segment, or capability constraints
- Represents realistic addressable opportunity
- Example: AI-powered email marketing for e-commerce in North America

**SOM (Serviceable Obtainable Market)**

- Realistic market share achievable in 3-5 years
- Accounts for competition, resources, and market dynamics
- Used for financial projections and fundraising
- Example: 2-5% of SAM based on competitive landscape

### When to Use Each Methodology

**Top-Down Analysis**

- Use when established market research exists
- Best for mature, well-defined markets
- Validates market existence and growth
- Starts with industry reports and narrows down

**Bottom-Up Analysis**

- Use when targeting specific customer segments
- Best for new or niche markets
- Most credible for investors
- Builds from customer data and pricing

**Value Theory**

- Use when creating new market categories
- Best for disruptive innovations
- Estimates based on value creation
- Calculates willingness to pay for problem solution

## Three-Methodology Framework

### Methodology 1: Top-Down Analysis

Start with total market size and narrow to addressable segments.

**Process:**

1. Identify total market category from research reports
2. Apply geographic filters (target regions)
3. Apply segment filters (target industries/customers)
4. Calculate competitive positioning adjustments

**Formula:**

TAM = Total Market Category Size
SAM = TAM × Geographic % × Segment %
SOM = SAM × Realistic Capture Rate (2-5%)


**When to use:** Established markets with available research (e.g., SaaS, fintech, e-commerce)

**Strengths:** Quick, uses credible data, validates market existence

**Limitations:** May overestimate for new categories, less granular

### Methodology 2: Bottom-Up Analysis

Build market size from customer segment calculations.

**Process:**

1. Define target customer segments
2. Estimate number of potential customers per segment
3. Determine average revenue per customer
4. Calculate realistic penetration rates

**Formula:**

TAM = Σ (Segment Size × Annual Revenue per Customer)
SAM = TAM × (Segments You Can Serve / Total Segments)
SOM = SAM × Realistic Penetration Rate (Year 3-5)


**When to use:** B2B, niche markets, specific customer segments

**Strengths:** Most credible for investors, granular, defensible

**Limitations:** Requires detailed customer research, time-intensive

### Methodology 3: Value Theory

Calculate based on value created and willingness to pay.

**Process:**

1. Identify problem being solved
2. Quantify current cost of problem (time, money, inefficiency)
3. Calculate value of solution (savings, gains, efficiency)
4. Estimate willingness to pay (typically 10-30% of value)
5. Multiply by addressable customer base

**Formula:**

Value per Customer = Problem Cost × % Solved by Solution
Price per Customer = Value × Willingness to Pay % (10-30%)
TAM = Total Potential Customers × Price per Customer
SAM = TAM × % Meeting Buy Criteria
SOM = SAM × Realistic Adoption Rate


**When to use:** New categories, disruptive innovations, unclear existing markets

**Strengths:** Shows value creation, works for new markets

**Limitations:** Requires assumptions, harder to validate

## Step-by-Step Process

### Step 1: Define the Market

Clearly specify what market is being measured.

**Questions to answer:**

- What problem is being solved?
- Who are the target customers?
- What's the product/service category?
- What's the geographic scope?
- What's the time horizon?

**Example:**

- Problem: E-commerce companies struggle with email marketing automation
- Customers: E-commerce stores with >$1M annual revenue
- Category: AI-powered email marketing software
- Geography: North America initially, global expansion
- Horizon: 3-5 year opportunity

### Step 2: Gather Data Sources

Identify credible data for calculations.

**Top-Down Sources:**

- Industry research reports (Gartner, Forrester, IDC)
- Government statistics (Census, BLS, trade associations)
- Public company filings and earnings
- Market research firms (Statista, CB Insights, PitchBook)

**Bottom-Up Sources:**

- Customer interviews and surveys
- Sales data and CRM records
- Industry databases (LinkedIn, ZoomInfo, Crunchbase)
- Competitive intelligence
- Academic research

**Value Theory Sources:**

- Customer problem quantification
- Time/cost studies
- ROI case studies
- Pricing research and willingness-to-pay surveys

### Step 3: Calculate TAM

Apply chosen methodology to determine total market.

**For Top-Down:**

1. Find total category size from research
2. Document data source and year
3. Apply growth rate if needed
4. Validate with multiple sources

**For Bottom-Up:**

1. Count total potential customers
2. Calculate average annual revenue per customer
3. Multiply to get TAM
4. Break down by segment

**For Value Theory:**

1. Quantify total addressable customer base
2. Calculate value per customer
3. Estimate pricing based on value
4. Multiply for TAM

### Step 4: Calculate SAM

Narrow TAM to serviceable addressable market.

**Apply Filters:**

- Geographic constraints (regions you can serve)
- Product limitations (features you currently have)
- Customer requirements (size, industry, use case)
- Distribution channel access
- Regulatory or compliance restrictions

**Formula:**

SAM = TAM × (% matching all filters)


**Example:**

- TAM: $10B global email marketing
- Geographic filter: 40% (North America)
- Product filter: 30% (e-commerce focus)
- Feature filter: 60% (need AI capabilities)
- SAM = $10B × 0.40 × 0.30 × 0.60 = $720M

### Step 5: Calculate SOM

Determine realistic obtainable market share.

**Consider:**

- Current market share of competitors
- Typical market share for new entrants (2-5%)
- Resources available (funding, team, time)
- Go-to-market effectiveness
- Competitive advantages
- Time to achieve (3-5 years typically)

**Conservative Approach:**

SOM (Year 3) = SAM × 2%
SOM (Year 5) = SAM × 5%


**Example:**

- SAM: $720M
- Year 3 SOM: $720M × 2% = $14.4M
- Year 5 SOM: $720M × 5% = $36M

### Step 6: Validate and Triangulate

Cross-check using multiple methods.

**Validation Techniques:**

1. Compare top-down and bottom-up results (should be within 30%)
2. Check against public company revenues in space
3. Validate customer count assumptions
4. Sense-check pricing assumptions
5. Review with industry experts
6. Compare to similar market categories

**Red Flags:**

- TAM that's too small (< $1B for VC-backed startups)
- TAM that's too large (unsupported by data)
- SOM that's too aggressive (> 10% in 5 years for new entrant)
- Inconsistency between methodologies (> 50% difference)

## Industry-Specific Considerations

### SaaS Markets

**Key Metrics:**

- Number of potential businesses in target segment
- Average contract value (ACV)
- Typical market penetration rates
- Expansion revenue potential

**TAM Calculation:**

TAM = Total Target Companies × Average ACV × (1 + Expansion Rate)


### Marketplace Markets

**Key Metrics:**

- Gross Merchandise Value (GMV) of category
- Take rate (% of GMV you capture)
- Total transactions or users

**TAM Calculation:**

TAM = Total Category GMV × Expected Take Rate


### Consumer Markets

**Key Metrics:**

- Total addressable users/households
- Average revenue per user (ARPU)
- Engagement frequency

**TAM Calculation:**

TAM = Total Users × ARPU × Purchase Frequency per Year


### B2B Services

**Key Metrics:**

- Number of target companies by size/industry
- Average project value or retainer
- Typical buying frequency

**TAM Calculation:**

TAM = Total Target Companies × Average Deal Size × Deals per Year


## Presenting Market Sizing

### For Investors

**Structure:**

1. Market definition and problem scope
2. TAM/SAM/SOM with methodology
3. Data sources and assumptions
4. Growth projections and drivers
5. Competitive landscape context

**Key Points:**

- Lead with bottom-up calculation (most credible)
- Show triangulation with top-down
- Explain conservative assumptions
- Link to revenue projections
- Highlight market growth rate

### For Strategy

**Structure:**

1. Addressable customer segments
2. Prioritization by opportunity size
3. Entry strategy by segment
4. Expected penetration timeline
5. Resource requirements

**Key Points:**

- Focus on SAM and SOM
- Show segment-level detail
- Connect to go-to-market plan
- Identify expansion opportunities
- Discuss competitive positioning

## Common Mistakes to Avoid

**Mistake 1: Confusing TAM with SAM**

- Don't claim entire market as addressable
- Apply realistic product/geographic constraints
- Be honest about serviceable market

**Mistake 2: Overly Aggressive SOM**

- New entrants rarely capture > 5% in 5 years
- Account for competition and resources
- Show realistic ramp timeline

**Mistake 3: Using Only Top-Down**

- Investors prefer bottom-up validation
- Top-down alone lacks credibility
- Always triangulate with multiple methods

**Mistake 4: Cherry-Picking Data**

- Use consistent, recent data sources
- Don't mix methodologies inappropriately
- Document all assumptions clearly

**Mistake 5: Ignoring Market Dynamics**

- Account for market growth/decline
- Consider competitive intensity
- Factor in switching costs and barriers

## Additional Resources

### Reference Files

For detailed methodologies and frameworks:

- **references/methodology-deep-dive.md** - Comprehensive guide to each methodology with step-by-step worksheets
- **references/data-sources.md** - Curated list of market research sources, databases, and tools
- **references/industry-templates.md** - Specific templates for SaaS, marketplace, consumer, B2B, and fintech markets

### Example Files

Working examples with complete calculations:

- **examples/saas-market-sizing.md** - Complete TAM/SAM/SOM for a B2B SaaS product
- **examples/marketplace-sizing.md** - Marketplace platform market opportunity calculation
- **examples/value-theory-example.md** - Value-based market sizing for disruptive innovation

Use these examples as templates for your own market sizing analysis. Each includes real numbers, data sources, and assumptions documented clearly.

## Quick Start

To perform market sizing analysis:

1. **Define the market** - Problem, customers, category, geography
2. **Choose methodology** - Bottom-up (preferred) or top-down + triangulation
3. **Gather data** - Industry reports, customer data, competitive intelligence
4. **Calculate TAM** - Apply methodology formula
5. **Narrow to SAM** - Apply product, geographic, segment filters
6. **Estimate SOM** - 2-5% realistic capture rate
7. **Validate** - Cross-check with alternative methods
8. **Document** - Show methodology, sources, assumptions
9. **Present** - Structure for audience (investors, strategy, operations)

For detailed step-by-step guidance on each methodology, reference the files in references/ directory. For complete worked examples, see examples/ directory.

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  • Antigravity: ~/.gemini/antigravity/skills/wshobson/agents/market-sizing-analysis/SKILL.md

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Source & attribution

This skill is categorized under Marketing & Growth and is published by W. Shobson, maintained in wshobson/agents.

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