# Market Sizing

> Estimate total addressable market (TAM), serviceable market (SAM), and obtainable market (SOM).

- Skill: `sethdford/market-sizing` (Agent Skill)
- Install (CLI): `npx skillmds@latest add sethdford/market-sizing`
- Raw SKILL.md: https://api.skillmd.com/api/skills/sethdford/market-sizing/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Product & Planning
- Author: sethdford (https://skillmd.com/u/sethdford)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/sethdford/market-sizing

---


# Market Sizing

Quantify the revenue opportunity through TAM, SAM, and SOM estimates grounded in data and assumptions.

## Context

You are sizing the financial opportunity. If you have market research, customer data, or pricing information, use it. Your goal is credible market estimates that guide investment decisions.

## Domain Context

- **TAM/SAM/SOM framework**: Total, serviceable, obtainable markets
- **Bottom-up vs. top-down**: Customer counts vs. total addressable market
- **Beachhead strategy (Moore)**: Start with most addressable segment
- **TAM expansion**: How does the market grow as you add features?

## Instructions

1. **Define TAM (top-down)**: Total addressable market globally; use industry reports
2. **Define SAM**: Addressable market with your product; be realistic about reach
3. **Define SOM**: Realistic capture in 1-3 years given resources and competition
4. **Calculate multiple ways**: Customer counts × ARPU vs. TAM research, compare approaches
5. **Document assumptions**: Customer count, ARPU, market growth, conversion rates
6. **Sensitivity analysis**: How does sizing change if assumptions shift 50%?

## Output Artifact

Market sizing document (2 pages):
- TAM estimate and derivation
- SAM estimate (your addressable market)
- SOM projection (1-3 years)
- Key assumptions (documented)
- Sensitivity analysis
- Sources and confidence levels

## Anti-Patterns

- **TAM as revenue target**: "Our TAM is $10B, so we'll hit $100M revenue" (unlikely)
- **Ignoring TAM contraction**: Some markets shrink; others consolidate
- **Using only top-down**: Without customer validation
- **Overly precise estimates**: "TAM is $4.3B" (provide ranges instead)

## Further Reading

- *Pricing Strategy* (Hermann Simon) — market size and value capture
- *Crossing the Chasm* (Moore) — beachhead market sizing
- *The Lean Product Playbook* (Dan Olsen) — market sizing frameworks