tam-sam-som-calculator

SKILL.md

Purpose

Guide product managers through calculating Total Addressable Market (TAM), Serviceable Available Market (SAM), and Serviceable Obtainable Market (SOM) for a product idea by asking adaptive, contextually relevant questions. Use this to build defensible market size estimates backed by real-world citations, economic projections, and population data—essential for pitching to investors, securing budget, or validating product-market fit.

This is not a back-of-napkin guess—it's a structured, citation-backed analysis that withstands scrutiny.

Key Concepts

TAM/SAM/SOM Framework

The three-tier market sizing model:

Total Addressable Market (TAM):

The total market demand for a product or service

"If we captured 100% of the market, what's the revenue?"

Broadest possible market (no constraints)

Serviceable Available Market (SAM):

The segment of TAM your company can realistically target

Narrowed by geography, firmographics, demographics, or product constraints

"Who can we actually reach with our product?"

Serviceable Obtainable Market (SOM):

The portion of SAM you can realistically capture

Accounts for competition, market constraints, go-to-market capacity

"What can we capture in the next 1-3 years?"

Why This Works

Top-down validation: TAM → SAM → SOM ensures estimates are grounded in reality

Investor-friendly: Standard framework VCs and execs understand

Citation-backed: Real data sources (Census, Statista, World Bank) add credibility

Adaptive: Questions adjust based on context (B2B vs. B2C, US vs. global, etc.)

Anti-Patterns (What This Is NOT)

Not a single-number guess: "The market is $10B" without supporting data

Not static: Markets evolve—reassess annually

Not a substitute for customer validation: Market size ≠ product-market fit

When to Use This

Pitching to investors or execs (need market size in deck)

Validating product ideas (is the market big enough?)

Prioritizing product lines (which has bigger opportunity?)

Setting growth targets (what's realistic to capture?)

When NOT to Use This

For internal tools with captive users (no external market)

Before defining the problem (market sizing requires clear problem space)

As the only validation (pair with customer research)

Facilitation Source of Truth

Use workshop-facilitation as the default interaction protocol for this skill.

It defines:

session heads-up + entry mode (Guided, Context dump, Best guess)

one-question turns with plain-language prompts

progress labels (for example, Context Qx/8 and Scoring Qx/5)

interruption handling and pause/resume behavior

numbered recommendations at decision points

quick-select numbered response options for regular questions (include Other (specify) when useful)

This file defines the domain-specific assessment content. If there is a conflict, follow this file's domain logic.

Application

Use template.md for the full fill-in structure.

This interactive skill asks up to 4 adaptive questions, offering enumerated context-aware options at each step. The agent adapts questions based on previous responses.

Step 0: Gather Context (Before Questions)

Agent suggests:

Before we begin, it's helpful to have product context. If available, please share:

For Your Own Product:

Website copy (homepage, product pages, value prop statements)

Marketing emails or landing pages

Product descriptions or positioning statements

Case studies or customer testimonials

Sales deck or pitch materials

If You Don't Have a Product Yet:

Find a similar or adjacent product (competitor or analog)

Copy their website homepage, product description, or landing page

We'll use this as a reference point for market sizing

You can paste this content directly, or we can proceed with a brief description.

Why this helps:

Marketing materials already contain target audience, pain points, and value props

Analyzing real content (yours or competitors') grounds the analysis in reality

You can benchmark against similar products' market positioning

Optional Helper Script (Deterministic Math)

If you already have population and ARPU numbers (or a TAM estimate), you can run a deterministic helper to compute TAM/SAM/SOM and generate a Markdown table. This script does not fetch data or write files.

python3 scripts/market-sizing.py --population 5400000 --arpu 1000 --sam-share 30% --som-share 10%

Question 1: Problem Space

Agent asks:
"Based on the context you've provided (or will describe), what problem space are you exploring for market sizing?"

Offer 4 enumerated examples (user can select by number or write custom):

B2B SaaS productivity — E.g., "Workflow automation for small business operations" (like Zapier, Integromat)

Consumer fintech — E.g., "Personal budgeting app for Gen Z users" (like Mint, YNAB)

Healthcare/telehealth — E.g., "Mental health support for remote workers" (like BetterHelp, Talkspace)

E-commerce enablement — E.g., "Payment processing for online sellers" (like Stripe, Square)

Or write your own problem space description based on the marketing materials you shared.

Tip: If you provided website copy or marketing materials, the agent can extract the problem space from phrases like:

"We help [target] solve [problem]"

"The #1 solution for [use case]"

Customer pain points in testimonials or case studies

User response: [Selection or custom description]

Question 2: Geographic Region

Agent asks:
"What geographic region are you targeting?"

Offer 4 enumerated options (adapted based on problem space):

United States — Best for detailed Census Bureau data, BLS stats, robust industry reports

European Union — Use Eurostat, local statistical agencies; note GDPR/compliance considerations

Global — World Bank, IMF data; broader but less granular

Specific country/region — E.g., "Canada," "Southeast Asia," "Latin America"

Or specify your own region.

User response: [Selection or custom]

Adaptation logic:

If user selected B2B SaaS (Question 1, Option 1) → Emphasize US/EU markets (mature SaaS adoption)

If user selected Consumer fintech (Question 1, Option 2) → Mention emerging markets (higher mobile adoption)

Question 3: Industry/Market Segments

Agent asks:
"What specific industry or market segments does this problem space relate to?"

Offer 4 enumerated options (adapted based on problem space + geography):

Example (if Question 1 = B2B SaaS, Question 2 = US):

SMB services sector — 5.4M businesses, $1.2T revenue (US Census, 2023)

Professional services (legal, accounting) — 1.1M firms, $850B revenue (IBISWorld, 2023)

Healthcare providers — 900K practices, $4T industry (BLS, 2023)

Tech/software companies — 500K firms, $1.8T revenue (Statista, 2023)

Or describe your own industry segment.

User response: [Selection or custom]

Adaptation logic:

If Question 1 = Consumer fintech, offer consumer segments (e.g., "Gen Z 18-25," "Millennials 25-40")

If Question 1 = Healthcare, offer segments (e.g., "Primary care physicians," "Therapists/counselors")

Question 4: Potential Customers (Demographics/Firmographics)

Agent asks:
"Who are the potential customers affected by this problem?"

Offer 4 enumerated options (adapted based on previous answers):

Example (if Question 1 = B2B SaaS, Question 3 = SMB services sector):

SMBs with 10-50 employees — 1.2M businesses, $400B revenue (Census Bureau, 2023)

SMBs with 50-250 employees — 600K businesses, $800B revenue (Census Bureau, 2023)

Solo entrepreneurs/freelancers — 3.5M self-employed, $200B revenue (BLS, 2023)

Service businesses with online presence — 2M businesses, $600B e-commerce (Statista, 2023)

Or describe your own customer segment (firmographics, demographics, income, etc.).

User response: [Selection or custom]

Output: Generate TAM/SAM/SOM Analysis

After collecting responses, the agent generates a structured analysis:

# TAM/SAM/SOM Analysis

**Problem Space:** [User's input from Question 1]
**Geographic Region:** [User's input from Question 2]
**Industry/Market Segments:** [User's input from Question 3]
**Potential Customers:** [User's input from Question 4]

---

## Total Addressable Market (TAM)

**Definition:** The total market demand if you captured 100% of potential customers in the problem space.

**Population Estimate:** [Calculated from data sources]
- **Source:** [Citation, e.g., "US Census Bureau, 2023"]
- **Calculation:** [Show math, e.g., "5.4M SMBs × $1.2T revenue = $1.2T TAM"]

**Market Size Estimate:** $[X] billion/million
- **Source:** [Industry report citation]
- **URL:** [Clickable link to source]

---

## Serviceable Available Market (SAM)

**Definition:** The segment of TAM you can realistically target with your product (narrowed by geography, firmographics, product fit).

**Segment of TAM:** [User's narrowed segment from Question 4]

**Population Estimate:** [Calculated]
- **Source:** [Citation]
- **Calculation:** [Show math, e.g., "1.2M SMBs with 10-50 employees"]

**Market Size Estimate:** $[X] billion/million
- **Source:** [Citation]
- **URL:** [Link]

**Assumptions:**
- [List key assumptions, e.g., "Assumes 50% of SMBs have budget for automation tools"]

---

## Serviceable Obtainable Market (SOM)

**Definition:** The portion of SAM you can realistically capture in the next 1-3 years, accounting for competition and market constraints.

**Realistically Capturable Market:** [Agent's estimation based on market maturity, competition]

**Population Estimate:** [Calculated]
- **Source:** [Citation]
- **Calculation:** [Show math, e.g., "1.2M SMBs × 5% market share (Year 1) = 60K customers"]

**Market Size Estimate:** $[X] million
- **Assumptions:**
  - [Competition assumption, e.g., "5 major competitors, market leader has 15% share"]
  - [GTM assumption, e.g., "Sales capacity: 50 customers/month in Year 1"]
  - [Conversion assumption, e.g., "10% trial-to-paid conversion"]

**Year 1-3 Projections:**
- **Year 1:** [X]K customers, $[X]M revenue (5% of SAM)
- **Year 2:** [X]K customers, $[X]M revenue (10% of SAM)
- **Year 3:** [X]K customers, $[X]M revenue (15% of SAM)

---

## Data Sources & Citations

- [Source 1: e.g., "US Census Bureau (2023). County Business Patterns. URL: census.gov"]
- [Source 2: e.g., "IBISWorld (2023). Professional Services Industry Report. URL: ibisworld.com"]
- [Source 3: e.g., "Statista (2023). SMB Software Market Size. URL: statista.com"]
- [Add all sources used]

---

## Validation Questions

1. **Does TAM align with industry reports?** [Compare to 3rd-party market research]
2. **Is SAM realistically serviceable?** [Can your GTM motion reach this segment?]
3. **Is SOM achievable given competition?** [Is 5-15% market share realistic in 3 years?]

---

## Next Steps

1. **Validate with customer interviews:** Does the problem resonate with target segment?
2. **Benchmark against competitors:** What market share do incumbents have?
3. **Refine SOM based on GTM capacity:** Can sales/marketing support this growth?
4. **Update annually:** Markets shift—reassess TAM/SAM/SOM yearly

---

**Would you like to refine any assumptions or explore a different segment?**

Examples

See examples/sample.md for a full TAM/SAM/SOM analysis example.

Mini example excerpt:

**TAM:** 5.4M SMBs × $2,000 ARPA = $10.8B
**SAM:** 1.2M SMBs × $2,000 ARPA = $2.4B
**SOM:** 5% of SAM = $120M

Common Pitfalls

Pitfall 1: TAM Without Citations

Symptom: "The market is $50B" (no source)

Consequence: Can't defend the number to investors or execs.

Fix: Cite industry reports (Gartner, IBISWorld, Statista) with URLs.

Pitfall 2: SOM Equals SAM

Symptom: "SAM is $5B, SOM is $5B" (assuming 100% capture)

Consequence: Unrealistic projection—no market has zero competition.

Fix: SOM should be 1-20% of SAM in Year 1-3, accounting for competition.

Pitfall 3: No Population Estimates

Symptom: Only dollar amounts, no customer counts

Consequence: Can't build sales/marketing plans without knowing customer volume.

Fix: Always include population (e.g., "1.2M businesses" or "60K customers in Year 1").

Pitfall 4: Static Assumptions

Symptom: TAM/SAM/SOM calculated once, never updated

Consequence: Stale data as markets shift.

Fix: Reassess annually. Markets grow/shrink, competition changes, new data emerges.

Pitfall 5: Ignoring GTM Constraints

Symptom: "SOM is 50% of SAM in Year 1" (but no sales team)

Consequence: SOM isn't realistic given GTM capacity.

Fix: Ground SOM in GTM constraints (sales capacity, marketing budget, conversion rates).

References

Related Skills

skills/positioning-statement/SKILL.md — TAM/SAM/SOM informs "For [target]" segment size

skills/problem-statement/SKILL.md — Problem space defines the market

skills/recommendation-canvas/SKILL.md — Market sizing informs business outcome projections

Optional Helpers

skills/tam-sam-som-calculator/scripts/market-sizing.py — Deterministic TAM/SAM/SOM calculator (no network access)

External Frameworks

Steve Blank, The Four Steps to the Epiphany (2005) — Market sizing for startups

Lean Startup methodology — Validate market size with experiments, not just desk research

Data Sources (For Citations)

US: US Census Bureau, Bureau of Labor Statistics, IBISWorld, Statista

Europe: Eurostat, local statistical agencies

Global: World Bank, IMF, Gartner, Forrester

Dean's Work

TAM/SAM/SOM Prompt Generator (multi-turn adaptive market sizing)

Skill type: Interactive
Suggested filename: tam-sam-som-calculator.md
Suggested placement: /skills/interactive/
Dependencies: None (standalone interactive skill)