fnd.r-sizing-markets

Original：🇺🇸 English

Translated

Calculates TAM/SAM/SOM and assesses market timing. Use when sizing markets, estimating addressable opportunity, analyzing market timing, or validating opportunity scale.

1installs

Sourcebellabe/lean-os

Added on2026-02-07

NPX Install

npx skill4agent add bellabe/lean-os fnd.r-sizing-markets

SKILL.md Content

View Translation Comparison →

Market Sizing

Calculate market opportunity with TAM/SAM/SOM and timing analysis.

Canvas Files

Reads: 00.mode.md (VENTURE/BOOTSTRAP affects size requirements)
Reads: 02.constraints.md (budget, team for SOM calculation)
Reads: 01.context.md (industry beliefs to validate)
Writes: 03.opportunity.md

Prerequisites

Before sizing market:

```
strategy/canvas/00.mode.md
```
must exist (mode affects TAM requirements)

If missing:

"Market sizing requires business mode from 00.mode.md.

VENTURE mode needs TAM >$1B for institutional investors.
BOOTSTRAP mode can target smaller, profitable niches.

Run fnd-architect agent first."

Process

Step 1: Load Context

Read from canvas:

Mode from 00.mode.md → determines size thresholds
Constraints from 02.constraints.md → informs SOM calculation
Beliefs from 01.context.md → hypotheses to validate

Step 2: Calculate TAM (Total Addressable Market)

Use BOTH methods, compare results:

Top-Down Method:

TAM = Industry size from reports × relevant segment %

Source: Gartner, Forrester, IBISWorld, Statista
Cite the report and year

Bottom-Up Method:

TAM = Total potential customers × Average revenue per customer

Count: How many could possibly buy?
Price: What would they pay annually?

Validation: If methods differ >50%, investigate why.

Step 3: Calculate SAM (Serviceable Addressable Market)

Apply filters to TAM:

SAM = TAM × Geographic filter × Segment filter × Technical filter

Filter Type	Example	Typical Reduction
Geographic	US only	30-50% of global
Segment	SMB only	20-40% of total
Technical	Cloud-ready	50-80% of segment
Vertical	E-commerce	Varies

Document each filter with rationale.

Step 4: Calculate SOM (Serviceable Obtainable Market)

Apply realistic capture based on constraints from 02.constraints.md:

SOM = SAM × Realistic market share %

Timeline	New Entrant	With Traction	Established
Year 1	0.5-1%	1-3%	3-5%
Year 3	2-5%	5-10%	10-15%
Year 5	5-10%	10-20%	15-25%

Constraint adjustments:

Limited budget → lower channel reach → lower SOM
Small team → slower sales velocity → lower SOM
Short runway → less time to penetrate → lower SOM

Step 5: Assess Market Timing

Why Now? Framework:

Factor	Question	Signals
Technology	What's newly possible?	Cost drops, capability jumps
Regulation	What's newly required/allowed?	New laws, compliance deadlines
Behavior	What habits changed?	Adoption curves, search trends
Economics	What's newly affordable?	Price/performance improvements
Competition	What gap exists?	Incumbent weakness, market void

Score each factor 1-5:

Timing Score = Technology + Regulation + Behavior + Economics + Competition

Score	Interpretation
>20	Strong timing — move fast
15-20	Good timing — proceed
10-15	Questionable — validate further
<10	Poor timing — reconsider

Step 6: Validate Against Mode

Mode	TAM Requirement	SAM Requirement
VENTURE	>$1B	>$100M
BOOTSTRAP	Any (profitable niche OK)	>$10M
HYBRID	>$500M	>$50M

If below threshold, flag:

"Market size concern for [MODE] mode:
- TAM: $[X] (requirement: $[Y])

Options:
1. Expand market definition
2. Adjacent market expansion
3. Reconsider mode (switch to BOOTSTRAP)"

Step 7: Write Output

Write to

strategy/canvas/03.opportunity.md

using output format below.

Output Format

markdown

# 03. Market Opportunity

## Market Size

| Level | Value | Method | Source |
|-------|-------|--------|--------|
| TAM | $[X]B | [Top-down/Bottom-up] | [Source, Year] |
| SAM | $[X]M | [Filters applied] | [Calculation] |
| SOM (3yr) | $[X]M | [Share %] × SAM | [Assumptions] |

## TAM Calculation

### Top-Down
- Industry: [Name]
- Total size: $[X] ([Source])
- Relevant segment: [X]% = $[X]

### Bottom-Up
- Potential customers: [N]
- Average deal size: $[X]/year
- TAM: [N] × $[X] = $[X]

### Reconciliation
[Explain any difference between methods]

## SAM Derivation

| Filter | Reduction | Remaining |
|--------|-----------|-----------|
| Starting TAM | - | $[X] |
| [Filter 1] | [X]% | $[X] |
| [Filter 2] | [X]% | $[X] |
| **SAM** | - | **$[X]** |

## SOM Assumptions

- Year 1 share: [X]% = $[X]
- Year 3 share: [X]% = $[X]
- Rationale: [Why these shares are achievable]

## Why Now

| Factor | Score | Evidence |
|--------|-------|----------|
| Technology | [1-5] | [What's newly possible] |
| Regulation | [1-5] | [What's changed] |
| Behavior | [1-5] | [What shifted] |
| Economics | [1-5] | [What's affordable] |
| Competition | [1-5] | [What gap exists] |
| **Total** | **[X]/25** | |

## Market Trends

### Tailwinds
- [Trend 1]: [Impact on opportunity]
- [Trend 2]: [Impact on opportunity]

### Headwinds
- [Trend 1]: [Mitigation strategy]
- [Trend 2]: [Mitigation strategy]

## Market Risks

| Risk | Probability | Impact | Mitigation |
|------|-------------|--------|------------|
| [Risk 1] | H/M/L | H/M/L | [Strategy] |
| [Risk 2] | H/M/L | H/M/L | [Strategy] |

## Mode Validation

**Mode:** [From 00.mode.md]
**TAM Requirement:** [Met/Not Met]
**Recommendation:** [Proceed/Expand/Reconsider]

Quality Criteria

Before finalizing, verify:

Both TAM methods calculated and reconciled
All SAM filters documented with rationale
SOM based on constraints, not aspirations
Timing score completed with evidence
Mode validation performed
Sources cited with years

Boundaries

Does NOT validate customer demand (see fnd.r-scoring-problems)
Does NOT guarantee market capture
Does NOT predict competitor response
Market size is estimate, not fact — cite sources
SOM is constrained projection, not target
Timing assessment is point-in-time, markets change
Does NOT handle multi-market or platform economics