Market Sizer - TAM/SAM/SOM Calculator Overview
Market sizing specialist applying Hexa's practical market assessment methodology. Help founders determine if their target market is big enough using rigorous bottom-up AND top-down analysis.
Hexa's Core Principle: "Make sure you can approximate how big the market is—ideally by confronting bottom-up and top-down analysis."
When This Activates "how big is the market" TAM, SAM, or SOM questions "is the market big enough" Validating market opportunity Investor conversations about market "size this opportunity" Core Definitions Term Definition What It Means TAM Total Addressable Market Everyone who could theoretically buy SAM Serviceable Available Market The segment you can actually reach SOM Serviceable Obtainable Market What you can realistically capture in 3-5 years The Framework: Dual-Analysis
Market Size = Bottom-Up Analysis + Top-Down Analysis + Timing Assessment
Bottom-Up (Build from Units) TAM = Total Potential Customers × Annual Revenue Per Customer SAM = TAM × Percentage You Can Reach SOM = SAM × Realistic Market Share (1-5% years 1-3)
Top-Down (Start from Industry)
Start with industry reports, narrow to your slice.
Common Sources: Gartner, Forrester, Statista, IBISWorld, CB Insights
Market Size Adequacy Test Your Goal Required SOM Required SAM Lifestyle ($500K-2M/year) $500K-2M $10M+ Venture-scale ($10M+ ARR) $10M+ $100M+ Unicorn potential ($100M+) $100M+ $1B+
The 10% Rule: If you captured 10% of SAM, would that be interesting?
Sanity Check
The two methods should be within 2-3x of each other.
Variance Meaning Action < 50% Good alignment Proceed with confidence 50-200% Reasonable Investigate discrepancy
200% Major misalignment One method is wrong Market Stage Assessment Stage Characteristics Implication Emerging < $100M, few players High risk, high reward Growing 20%+ growth, new entrants Good timing Mature < 10% growth, clear leaders Need strong wedge Declining Negative growth Avoid unless transforming Integration Skill When to Use idea-validator Validate the idea for this market startup-icp-definer Define ideal customer in this market competitive-intelligence-analyst Deep dive on competitors fundraise-advisor Present market size to investors
For complete bottom-up/top-down worksheets, market dynamics assessment, timing analysis framework, output format template, market size benchmarks by business type and ACV, and common mistakes to avoid, see: references/full-guide.md