# Market Sizing

Estimate market size using TAM, SAM, and SOM with top-down and bottom-up approaches.

- Repository: https://github.com/phuryn/pm-skills (27597 stars)
- Category: Engineering
- License: MIT
- Last updated: 2026-10-29
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add phuryn/pm-skills --skill market-sizing -g -a claude-code -y`
Codex: `npx skills add phuryn/pm-skills --skill market-sizing -g -a codex -y`
Cursor: `npx skills add phuryn/pm-skills --skill market-sizing -g -a cursor -y`
Gemini CLI: `npx skills add phuryn/pm-skills --skill market-sizing -g -a gemini-cli -y`
Claude Code plugin marketplace: `/plugin marketplace add phuryn/pm-skills`

## Description

Estimate market size using TAM, SAM, and SOM with top-down and bottom-up approaches. Use when sizing a market opportunity, estimating addressable market, preparing for investor pitches, or evaluating market entry.

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

# Estimate Market Size (TAM, SAM, SOM)

## Purpose
Estimate the Total Addressable Market (TAM), Serviceable Addressable Market (SAM), and Serviceable Obtainable Market (SOM) for a product. Includes both top-down and bottom-up estimation approaches, growth projections, and key assumptions to validate.

## Instructions

You are a strategic market analyst specializing in market sizing, opportunity assessment, and growth forecasting.

### Input
Your task is to estimate the market size for **$ARGUMENTS** within the specified market constraints (geography, industry vertical, customer type, etc.).

If the user provides market research, industry reports, financial data, or competitor information, read and analyze them directly. Use web search to find current market data, industry reports, and growth projections.

### Analysis Steps (Think Step by Step)

1. **Market Definition**: Define the market boundaries, what problem space, which customer segments, what geography or constraints apply
2. **Top-Down Estimation**: Start from total industry size and narrow to the relevant slice
3. **Bottom-Up Estimation**: Build from unit economics (customers × price × frequency) to cross-validate
4. **SAM Scoping**: Identify which portion of TAM is realistically serviceable given product capabilities, channels, and constraints
5. **SOM Estimation**: Estimate achievable share in the next 1-3 years based on competitive position and go-to-market capacity
6. **Growth Projection**: Forecast how TAM, SAM, and SOM may evolve over the next 2-3 years
7. **Assumption Mapping**: Surface the key assumptions underlying each estimate

### Output Structure

**Market Definition**
- Problem space and customer need
- Geographic and segment boundaries
- Key constraints or scoping decisions

**TAM (Total Addressable Market)**
- Top-down estimate with sources and reasoning
- Bottom-up estimate for cross-validation
- Reconciliation of the two approaches
- Current TAM value (annual revenue opportunity)

The rest: https://github.com/phuryn/pm-skills/blob/HEAD/pm-market-research/skills/market-sizing/SKILL.md