Tam Sam Som Calculator

Purpose

Guide PMs through calculating TAM, SAM, and SOM using both top-down and bottom-up approaches — producing defensible market size estimates for strategy, fundraising, and prioritization.

Application

Turn 1: Market Definition

Agent asks: "What market are you sizing?"

• Product/service
• Category
• Geographic scope
• Current vs. future market?

Turn 2: Top-Down Approach

Agent asks: "Let's start with industry data."

## Top-Down Market Sizing

### TAM (Total Addressable Market)
**Definition:** Total revenue opportunity if 100% market share
**Approach:** Industry report data × average revenue per customer
- Industry size: $[X]B (source: [Report])
- Relevant segment: [%] of total = $[X]B
- **TAM: $[X]B**

### SAM (Serviceable Addressable Market)
**Definition:** Portion of TAM our product can serve
**Filters applied:**
- Geography: [Countries/regions we serve]
- Company size: [Our target segment]
- Technology fit: [Who can actually use our product]
- **SAM: $[X]M** ([X]% of TAM)

### SOM (Serviceable Obtainable Market)
**Definition:** Realistic capture in 3-5 years
**Factors:**
- Current market share: [%]
- Growth rate: [% per year]
- Competitive intensity: [High/Med/Low]
- **SOM: $[X]M** ([X]% of SAM)

Turn 3: Bottom-Up Validation

Agent asks: "Let's validate with bottom-up math."

## Bottom-Up Validation

**Target customers:** [# potential customers matching our ICP]
**× Average revenue per customer:** $[X]/year
**× Expected penetration rate:** [X]%
**= Bottom-up SOM:** $[X]M

**Top-down vs Bottom-up comparison:**
- Top-down SOM: $[X]M
- Bottom-up SOM: $[X]M
- Delta: [%] — [Explanation of difference]

Output

# Market Sizing: [Product/Market]

| Metric | Value | Method |
|--------|-------|--------|
| **TAM** | $[X]B | Top-down from industry data |
| **SAM** | $[X]M | TAM filtered by segments we can serve |
| **SOM** | $[X]M | Bottom-up validated, 3-year target |

**Key assumptions:**
- [Assumption 1]
- [Assumption 2]

**Sensitivity:**
- If [assumption changes], SOM ranges from $[X]M to $[Y]M

References

Related Skills

• skills/strategy/business-model-canvas/SKILL.md — Revenue model context
• skills/launch/gtm-strategy/SKILL.md — Market segments
• skills/analytics/business-health-diagnostic/SKILL.md — Business health

Skill type: Interactive Domain: Analytics & Metrics