market-sizing-analysis

Use it when:: You need market size figures for a pitch deck or business plan, or to decide whether a market is worth entering.
It does:: Defines the market, gathers sources, calculates total, serviceable and obtainable market with up to three methods, then cross-checks the results.
You get:: TAM, SAM and SOM with the method, sources and assumptions behind each, laid out for investors or for strategy.
Terms:: TAM is all revenue at 100% share, SAM the part your product can serve, SOM the share you can realistically win in 3–5 years.
Red flags:: A TAM under $1B for a VC-backed startup, an SOM above 10% in five years, or methods more than 50% apart.

TL;DR

A market sizing method that needs no tool or data service. The SKILL.md defines the three tiers and when each method fits; a reference file holds the formulas and steps. Top-down starts from an industry report's category size and narrows it by geography and segment. Bottom-up multiplies the customers in each segment by their yearly revenue, the method it calls most credible to investors. Value theory prices the solution at 10–30% of the value it creates, for new categories with no market data. The six steps define the market (problem, customers, category, geography, time horizon), gather sources such as analyst reports, census data, Crunchbase or customer interviews, calculate TAM, filter it down to SAM, take 2–5% of SAM as SOM, then triangulate: top-down and bottom-up results should land within 30% of each other. It gives TAM formulas for SaaS, marketplace, consumer and B2B services markets, outlines for presenting to investors (lead with bottom-up) or for strategy, and five common mistakes, such as confusing TAM with SAM or relying on top-down figures alone.

Summarizes the skill at 4bde316.

npx skills add https://github.com/wshobson/agents --skill market-sizing-analysis

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Category	category:business Run a company outside its code and marketing: strategy, sales, finance, operations, legal, management and hiring.
Type	type:workflow A multi-step process the agent follows: interview, debug, run a TDD loop, review.
Effect	effect:none Adds no side effects of its own. It shapes how the agent thinks, writes or reviews. Guidelines and routers are always effect:none, even when the task they support edits code.
Needs	needs:none Instructions only. Works in any agent that supports skills.
Publisher	by:community Everyone else. Unverified vendor claims default to community.
Topics	finance research

SKILL.md

From wshobson/agents at 4bde316. Checked daily, last changed Nov 6, 2026.

Frontmatter

name: market-sizing-analysis
description: Calculate TAM/SAM/SOM for market opportunities using top-down, bottom-up, and value theory methodologies. Use this skill when sizing markets, estimating addressable revenue, validating market opportunity for a new venture, or building investor-ready market analysis for a startup pitch or business plan.
version: 1.0.0

Market Sizing Analysis

Comprehensive market sizing methodologies for calculating Total Addressable Market (TAM), Serviceable Available Market (SAM), and Serviceable Obtainable Market (SOM) for startup opportunities.

Overview

Market sizing provides the foundation for startup strategy, fundraising, and business planning. Calculate market opportunity using three complementary methodologies: top-down (industry reports), bottom-up (customer segment calculations), and value theory (willingness to pay).

Core Concepts

The Three-Tier Market Framework

TAM (Total Addressable Market)

Total revenue opportunity if achieving 100% market share
Defines the universe of potential customers
Used for long-term vision and market validation
Example: All email marketing software revenue globally

SAM (Serviceable Available Market)

Portion of TAM targetable with current product/service
Accounts for geographic, segment, or capability constraints
Represents realistic addressable opportunity
Example: AI-powered email marketing for e-commerce in North America

SOM (Serviceable Obtainable Market)

Realistic market share achievable in 3-5 years
Accounts for competition, resources, and market dynamics
Used for financial projections and fundraising
Example: 2-5% of SAM based on competitive landscape

When to Use Each Methodology

Top-Down Analysis

Use when established market research exists
Best for mature, well-defined markets
Validates market existence and growth
Starts with industry reports and narrows down

Bottom-Up Analysis

Use when targeting specific customer segments
Best for new or niche markets
Most credible for investors
Builds from customer data and pricing

Value Theory

Use when creating new market categories
Best for disruptive innovations
Estimates based on value creation
Calculates willingness to pay for problem solution

Detailed patterns and worked examples

Detailed pattern documentation lives in references/details.md. Read that file when the navigation tier above is insufficient.