Market Sizing

Market Sizing for Entry: TAM, SAM, SOM Methodology

Market sizing methodology for market entry: TAM, SAM, SOM with bottom-up validation, pitfalls, defensible sizing for board approval.

Defensible Market Sizing Wins Board Approval

Most market sizing fails executive scrutiny because it relies on unsourced top-down numbers. Defensible sizing combines top-down (industry research) with bottom-up (account/customer-level estimation), reconciles within tolerance, and documents every assumption. The output: TAM, SAM, SOM that the board funds.

Key Capabilities

01.

TAM Methodology

Total addressable market with multiple sources reconciled.

02.

SAM Methodology

Serviceable addressable market with capability constraints.

03.

SOM Methodology

Serviceable obtainable market with realistic share assumptions.

04.

Bottom-Up Validation

Account/customer-level sizing reconciled with top-down.

05.

Sensitivity Analysis

Best/base/worst case with documented assumptions.

06.

Pitfalls

Common pitfalls: hockey-stick assumptions, unsourced figures, over-attribution.

80+
Sizing Studies
20-30%
Reconciliation Tolerance
TAM/SAM/SOM
Standard Output
4.8/5
Board Approval

Process

01

Top-Down Sizing

Industry research, analyst reports, public data.

02

Bottom-Up Sizing

Account-level estimation per segment.

03

Reconciliation

Reconcile within 20-30% tolerance.

04

Sensitivity

Best/base/worst case modeling.

Benefits

Defensible Numbers

Reconciled methodology builds executive trust.

Faster Approval

Documented assumptions speed approval cycles.

Investment Sizing

Sizing right-sizes investment to opportunity.

Risk Awareness

Sensitivity analysis surfaces risks early.

Frameworks & Tools

  • — IDC
  • — Gartner
  • — Forrester
  • — Industry research
  • — Customer interviews

Industries

  • — SaaS
  • — Financial Services
  • — Healthcare
  • — Manufacturing
  • — Retail
  • — Energy

FAQ

TAM vs SAM vs SOM?
TAM: total market. SAM: market we can serve. SOM: realistic share within SAM. All three needed for credible sizing.
Common pitfalls?
Hockey-stick assumptions. Unsourced figures. Over-attribution. Each kills credibility.
Sources?
IDC, Gartner, Forrester, McKinsey for top-down. Customer interviews and account analysis for bottom-up.
Refresh?
Annual minimum. After major market shifts, refresh.

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