# Market Sizing

> Calculate TAM/SAM/SOM using both top-down and bottom-up approaches with clear assumption tracking. Use when: market size, tam sam som, market opportunity, addressable market.

- Skill: `varunk130/market-sizing` (Agent Skill)
- Install (CLI): `npx skillmds@latest add varunk130/market-sizing`
- Raw SKILL.md: https://api.skillmd.com/api/skills/varunk130/market-sizing/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: varunk130 (https://skillmd.com/u/varunk130)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/varunk130/market-sizing

---


# Market Sizing Calculator

Calculate TAM/SAM/SOM using both top-down and bottom-up approaches with clear assumption tracking.

## When to Use This Skill
- New product business cases
- Expansion into new markets or segments
- Investor/board presentations

## What You'll Need
- Clear definition of your market boundaries
- Industry data or reports (for top-down)
- Unit economics inputs (for bottom-up)

## Process

### Step 1: Check Your Context
Read context files for company, product, personas, and competitor data.

### Step 2: Define Market Boundaries
Define geography, customer segment, and use case boundaries.

### Step 3: Top-Down Analysis
Start with total market and narrow down using industry reports and public filings.

### Step 4: Bottom-Up Analysis
Build up from unit economics: potential customers x deal size x frequency.

### Step 5: Triangulate
Compare approaches. Aligned = high confidence. Divergent = investigate.

### Step 6: Document Assumptions
Every number gets a source or explicit assumption marker.

## Framework Reference

**TAM-SAM-SOM** with dual methodology:
- Top-down: Market reports - narrow to segment
- Bottom-up: Unit economics - multiply out
- Triangulation increases confidence

## Tips for Best Results
1. Keep context files updated
2. Be conservative - optimistic estimates lose credibility
3. Show your work - transparent assumptions > black box
4. Multiple approaches - if they diverge, you're missing something