# Market Sizer > This skill sizes the total addressable, serviceable, and obtainable market for a product opportunity. Use when asked to estimate market size, calculate TAM/SAM/SOM, or validate whether an opportunity is large enough to pursue. Also consider when a PRD or initiative brief lacks quantified market context. Suggest when the team is about to commit engineering resources to an opportunity without understanding its revenue ceiling. - Skill: `mittuled/market-sizer` (Agent Skill, multi-file: 6 files) - Install (CLI): `npx skillmds@latest add mittuled/market-sizer` - Raw SKILL.md: https://api.skillmd.com/api/skills/mittuled/market-sizer/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Product & Planning - Author: mittuled (https://skillmd.com/u/mittuled) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/mittuled/market-sizer --- # market-sizer ## Agent: Product Manager L2 product manager (multi-instance) responsible for customer discovery, requirements extraction, sprint planning, backlog management, and go-live approval. Bridges customer needs and engineering delivery. Department ethos: [ideal-product.md](../../../../departments/product/ideal-product.md) ## Skill Description Sizes the total addressable, serviceable, and obtainable market for a product opportunity using top-down and bottom-up estimation methods. ## When to Use - When a new product opportunity needs quantified market context before entering the roadmap - When leadership requests a revenue ceiling estimate to prioritize between competing initiatives - When an existing market sizing is stale (older than two quarters) or based on assumptions that have shifted due to competitive moves or regulatory changes ## Workflow 1. **Define the market boundary**: Identify the target customer segment, geography, and use case. Exclude adjacent segments that the product cannot credibly serve today. Deliverable: one-paragraph market definition with explicit inclusion and exclusion criteria. 2. **Estimate TAM (top-down)**: Pull industry reports, analyst estimates, and public filings to calculate the total addressable market in annual revenue terms. Cross-check at least two independent sources. Deliverable: TAM figure with source citations and confidence rating (high/medium/low). 3. **Estimate SAM (bottom-up)**: Narrow TAM to the segment reachable with the current product capabilities, pricing model, and go-to-market channels. Multiply estimated reachable accounts by average contract value. Deliverable: SAM figure with assumptions table. 4. **Estimate SOM**: Apply realistic penetration assumptions based on competitive intensity, sales capacity, and time horizon (typically 3 years). Deliverable: SOM figure with penetration rate justification. 5. **Triangulate and stress-test**: Compare top-down and bottom-up estimates. Flag any divergence greater than 2x and investigate. Run sensitivity analysis on the two most uncertain assumptions. Deliverable: summary table showing TAM/SAM/SOM with confidence intervals. 6. **Package for decision-makers**: Assemble a one-page market sizing brief suitable for inclusion in a PRD, investment memo, or roadmap review. Deliverable: formatted brief with key figures, assumptions, sources, and recommendation on whether the opportunity clears the minimum threshold. ## Anti-Patterns - **Single-source sizing**: Relying on one analyst report without cross-validation. *Why*: Analyst methodologies vary widely; a single source can overstate or understate by 3-5x, leading to misallocated resources. - **TAM-only thinking**: Presenting the total addressable market as if it were capturable revenue. *Why*: TAM ignores competitive dynamics, distribution constraints, and product gaps, giving leadership a dangerously inflated picture. - **Static snapshots**: Sizing the market once and never revisiting as conditions change. *Why*: Markets shift with new entrants, regulation, and technology changes; stale numbers silently corrupt downstream prioritization decisions. ## Output **On success**: A market sizing brief containing TAM, SAM, and SOM figures with confidence intervals, an assumptions table, source citations, and a go/no-go recommendation -- formatted for embedding in a PRD or roadmap review deck. **On failure**: Report which estimates could not be completed (missing data sources, unreliable segment definitions, irreconcilable top-down vs. bottom-up gap), what was attempted, and recommend specific data acquisitions or customer interviews to close the gaps. ## Related Skills - [`backlog-groomer`](../backlog-groomer/SKILL.md) — sibling skill under the same agent — combine with backlog-groomer for end-to-end coverage - [`backlog-populator`](../backlog-populator/SKILL.md) — sibling skill under the same agent — combine with backlog-populator for end-to-end coverage - [`customer-discovery-planner`](../customer-discovery-planner/SKILL.md) — sibling skill under the same agent — combine with customer-discovery-planner for end-to-end coverage - [`demand-validator`](../demand-validator/SKILL.md) — sibling skill under the same agent — combine with demand-validator for end-to-end coverage - [`dependency-mapper-review`](../dependency-mapper-review/SKILL.md) — sibling skill under the same agent — combine with dependency-mapper-review for end-to-end coverage - [`dependency-resolver`](../dependency-resolver/SKILL.md) — sibling skill under the same agent — combine with dependency-resolver for end-to-end coverage - [`design-approval`](../design-approval/SKILL.md) — sibling skill under the same agent — combine with design-approval for end-to-end coverage - [`flow-designer-review`](../flow-designer-review/SKILL.md) — sibling skill under the same agent — combine with flow-designer-review for end-to-end coverage - [`go-live-approver`](../go-live-approver/SKILL.md) — sibling skill under the same agent — combine with go-live-approver for end-to-end coverage - [`internal-demo-runner`](../internal-demo-runner/SKILL.md) — sibling skill under the same agent — combine with internal-demo-runner for end-to-end coverage - [`jtbd-to-stories`](../jtbd-to-stories/SKILL.md) — sibling skill under the same agent — combine with jtbd-to-stories for end-to-end coverage - [`launch-checklist-runner`](../launch-checklist-runner/SKILL.md) — sibling skill under the same agent — combine with launch-checklist-runner for end-to-end coverage - [`risk-register-builder`](../risk-register-builder/SKILL.md) — sibling skill under the same agent — combine with risk-register-builder for end-to-end coverage - [`story-writer`](../story-writer/SKILL.md) — sibling skill under the same agent — combine with story-writer for end-to-end coverage - [`milestone-definer`](../milestone-definer/SKILL.md) — sibling skill under the same agent — combine with milestone-definer for end-to-end coverage - [`performance-budget-setter`](../performance-budget-setter/SKILL.md) — sibling skill under the same agent — combine with performance-budget-setter for end-to-end coverage - [`phase-planner`](../phase-planner/SKILL.md) — sibling skill under the same agent — combine with phase-planner for end-to-end coverage - [`phase-scope-adjuster`](../phase-scope-adjuster/SKILL.md) — sibling skill under the same agent — combine with phase-scope-adjuster for end-to-end coverage - [`pmm-pre-briefer`](../pmm-pre-briefer/SKILL.md) — sibling skill under the same agent — combine with pmm-pre-briefer for end-to-end coverage - [`requirements-extractor`](../requirements-extractor/SKILL.md) — sibling skill under the same agent — combine with requirements-extractor for end-to-end coverage - [`roadmap-placer`](../roadmap-placer/SKILL.md) — sibling skill under the same agent — combine with roadmap-placer for end-to-end coverage - [`scope-boundary-setter`](../scope-boundary-setter/SKILL.md) — sibling skill under the same agent — combine with scope-boundary-setter for end-to-end coverage - [`spec-translator`](../spec-translator/SKILL.md) — sibling skill under the same agent — combine with spec-translator for end-to-end coverage - [`sprint-planner`](../sprint-planner/SKILL.md) — sibling skill under the same agent — combine with sprint-planner for end-to-end coverage - [`sprint-reviewer`](../sprint-reviewer/SKILL.md) — sibling skill under the same agent — combine with sprint-reviewer for end-to-end coverage - [`support-pre-briefer`](../support-pre-briefer/SKILL.md) — sibling skill under the same agent — combine with support-pre-briefer for end-to-end coverage - [`third-party-integrator-review`](../third-party-integrator-review/SKILL.md) — sibling skill under the same agent — combine with third-party-integrator-review for end-to-end coverage - [`uat-coordinator`](../uat-coordinator/SKILL.md) — sibling skill under the same agent — combine with uat-coordinator for end-to-end coverage - [`user-researcher`](../user-researcher/SKILL.md) — sibling skill under the same agent — combine with user-researcher for end-to-end coverage