takumaoshiro TAM Estimation (市場規模・TAM推定)
Estimate Total Addressable Market (TAM), Serviceable Addressable Market (SAM), and Serviceable Obtainable Market (SOM) — designed for strategy teams, investors, and business development.
1. Overview
- Purpose: Quantify the total market opportunity and derive realistic obtainable market size using multiple estimation methodologies
- Audience: Strategy teams, investors, business development
- Frequency: Ad-hoc (new market entry, fundraising, annual strategy review)
- Time to complete: 2–5 hours (depending on data availability)
When to use
Use when evaluating a new market opportunity, preparing investor materials, planning market entry strategy, or conducting annual strategic reviews. Essential for go/no-go decisions on new business lines, geographic expansion, or product launches.
2. Input Data
Required
| Data Source | Format | Description |
|---|---|---|
| Industry reports | PDF / Web | Market size data from research firms (Gartner, IDC, Statista, etc.) |
| Government statistics | CSV / PDF | Census data, industry output statistics, economic indicators |
| Competitor revenue data | Spreadsheet / Web | Public revenue figures, estimated market shares |
| Pricing model | Spreadsheet | Product/service pricing tiers and average contract value |
| Target customer segments | Document | Defined customer personas, firmographics, and geographic scope |
Optional
| Data Source | Format | Description |
|---|---|---|
| Customer survey data | CSV | Willingness-to-pay, adoption intent, feature priorities |
| Adjacent market data | PDF / CSV | Related market sizes for analogy-based estimation |
| Historical growth data | CSV | Past market size figures for trend extrapolation |
| Regulatory landscape | Document | Regulations that expand or constrain the addressable market |
Data Quality Checks
- Verify data recency (industry reports should be within 2 years)
- Cross-reference at least 2 independent sources for key figures
- Confirm currency and geographic scope consistency across sources
- Check that competitor revenue data uses comparable definitions (ARR vs. total revenue)
3. Analysis Steps
Step 1: Define Market Boundaries
Clearly define the product/service category, geographic scope, customer segments, and time horizon. Document inclusion/exclusion criteria to ensure consistent scoping.
Step 2: Top-Down Sizing
Start from the total industry size and narrow down by applying relevant percentage filters: geographic region, product category, customer segment, and willingness to adopt. Formula: TAM(top-down) = Industry Total * Relevant Geography % * Relevant Segment % * Product Fit %.
Step 3: Bottom-Up Sizing
Count the number of potential customers in the target segment and multiply by average revenue per user (ARPU). Formula: TAM(bottom-up) = # Target Customers * Average Annual Revenue per Customer.
Step 4: Value Theory Approach
Estimate the total value the product/service delivers to customers and calculate the capturable share. Formula: TAM(value) = Total Value Created * Value Capture Rate.
Step 5: Cross-Validation
Compare top-down and bottom-up estimates. They should be within 2x of each other. If the gap is larger, revisit assumptions in both approaches. Document reconciliation notes.
Step 6: SAM Derivation
From the TAM, filter to the Serviceable Addressable Market by applying constraints: current product capabilities, distribution reach, language/localization, regulatory access. SAM = TAM * Serviceability Filters.
Step 7: SOM Estimation
Estimate the realistic obtainable market share over 3–5 years based on: go-to-market capacity, competitive intensity, brand strength, and sales cycle length. Use competitor market share as a benchmark. SOM = SAM * Realistic Market Share %.
Step 8: Growth Projection
Project TAM/SAM/SOM over 3–5 years using identified growth drivers: market CAGR, digital transformation trends, regulatory changes, and expansion plans. Provide low/mid/high scenarios.
Step 9: Confidence Assessment
Rate confidence level (high/medium/low) for each estimate based on data quality and assumption strength. Document key assumptions and sensitivity factors.
4. Output Format
Summary (top-level)
One-paragraph market opportunity statement with headline TAM/SAM/SOM figures, primary methodology used, and confidence level.
Detail sections
- TAM/SAM/SOM Waterfall — Visual funnel showing how TAM narrows to SAM to SOM with filter descriptions
- Methodology Explanation — Step-by-step breakdown of top-down, bottom-up, and value theory approaches with formulas and inputs
- Growth Projections (3–5 Year) — Year-by-year projections with low/mid/high scenarios and CAGR
- Confidence Intervals — Range estimates for each tier (e.g., TAM: ¥500B–¥800B) with confidence rating
- Data Sources & Assumptions — Complete list of sources, key assumptions, and their sensitivity impact
Visualizations
- TAM/SAM/SOM waterfall (nested circles or funnel chart)
- Top-down vs. bottom-up comparison bar chart
- 3–5 year growth projection line chart with scenario bands
- Market share composition pie chart (competitors + white space)
5. Judgment Criteria
| Metric | Healthy | Warning | Concern |
|---|---|---|---|
| TAM/SAM ratio | SAM > 10% of TAM | SAM 5–10% of TAM | SAM < 5% of TAM (too niche) |
| SOM/SAM ratio | SOM 5–20% of SAM | SOM < 5% (conservative) | SOM > 20% (aggressive) |
| Top-down vs. bottom-up gap | Within 2x | 2–3x difference | >3x difference (revisit) |
| Data recency | < 1 year old | 1–2 years old | > 2 years old |
| Source diversity | 3+ independent sources | 2 sources | 1 source only |
Decision Rules
- If TAM/SAM ratio <10%, classify as niche market — requires focused strategy justification
- If SOM >20% of SAM, flag as aggressive — demand concrete evidence of competitive advantage
- If top-down and bottom-up estimates differ by >2x, do NOT proceed — reconcile assumptions first
- Always cross-validate with at least one competitor's known revenue as a sanity check
- If data sources are >2 years old, apply a confidence discount and note the limitation prominently
- Growth projections >30% CAGR require exceptional justification (new regulation, technology shift)
6. Examples
Sample Input
Product: SaaS Marketing Automation for SMBs
Geography: Japan
Target: Companies with 50–500 employees
Pricing: ¥50,000/month average (¥600,000/year)
Industry: Digital Marketing Software
Industry Total (Global): $25B
Japan share: 8%
SMB segment: 35%
Sample Output
## TAM/SAM/SOM Summary
- TAM (Japan Digital Marketing Software): ¥300B ($2.0B)
- Top-down: $25B global * 8% Japan = $2.0B
- Bottom-up: 180,000 target companies * ¥600K = ¥108B (narrower product scope)
- Reconciled TAM: ¥200–300B range
- SAM (SMB segment, current product fit): ¥70B
- TAM * 35% SMB * 65% product-fit = ¥70B
- SOM (3-year obtainable): ¥3.5B
- SAM * 5% market share = ¥3.5B
- Implies ~5,800 customers at ¥600K ARPU
## Confidence: Medium
- Top-down based on IDC 2025 report (reliable)
- Bottom-up company count from government SMB statistics (reliable)
- Pricing assumption needs validation via customer interviews
7. Do's and Don'ts
Do
- Always use at least two sizing methodologies (top-down + bottom-up)
- Cross-validate estimates against known competitor revenues
- Document every assumption explicitly with source references
- Present ranges rather than single-point estimates
- Include a clear confidence rating for each figure
Don't
- Don't rely on a single data source for the TAM figure
- Don't confuse TAM with SAM — TAM is the total market, not your reachable portion
- Don't project SOM >20% of SAM without exceptional justification
- Don't use outdated market reports (>3 years) without heavy caveats
- Don't ignore market constraints (regulation, localization, distribution)
- Don't present growth projections without scenario analysis (low/mid/high)
8. Agent Guide
When executing this analysis skill:
You are performing TAM Estimation analysis.
Key rules:
- Always calculate TAM using at least two methods: top-down and bottom-up
- Cross-validate: top-down and bottom-up must be within 2x of each other
- TAM/SAM ratio <10% = niche market, flag for discussion
- SOM >20% of SAM = aggressive, require justification
- Present all figures as ranges with confidence levels
- Document every assumption and data source explicitly
- Growth projections must include low/mid/high scenarios
Refer to the full SKILL.md for thresholds, output format, and detailed steps.