Objective

Learn to quantify market size at three levels to set realistic growth expectations and identify where to focus your go-to-market efforts.

Instructions

1. Understand the Framework

TAM (Total Addressable Market): The total market demand for your product if you captured 100% market share with no limitations. Maximum revenue opportunity.

SAM (Serviceable Available Market): The segment of TAM that is reachable and relevant given your business model, geography, product scope, and distribution channels.

SOM (Serviceable Obtainable Market): The portion of SAM you can realistically capture in the short-to-mid term given current resources, competition, and capabilities.

2. Calculate Your TAM

Top-Down Approach:

• Start with industry research, market reports, or competitor data
• Use total market size from sources like Gartner, Forrester, or industry associations
• Example: "Global CRM software market = $69B in 2024"

Bottom-Up Approach:

• Count total potential customers × average annual contract value
• Example: "500,000 companies with 50+ employees × $10K ACV = $5B TAM"

Your TAM Calculation:

Method used: [Top-down / Bottom-up / Hybrid]

Data sources:

-

-

Calculation:

Your TAM: $_

Assumptions made:

-

-

3. Define Your SAM

Narrow TAM by applying filters that define your realistic target:

Geographic Filter:

• Are you US-only, North America, global?
• What % of TAM is in your operating regions?

Product Scope Filter:

• Does your product serve a specific segment of the broad market?
• Example: If TAM is all CRM, but you only do CRM for healthcare → filter to healthcare vertical

Pricing/Customer Size Filter:

• What company sizes can afford your solution?
• If you sell enterprise at $50K+, exclude SMBs from SAM

Distribution Channel Filter:

• Can you reach all customers, or only those accessible via your channels?
• Example: If you sell through AWS Marketplace, only count AWS users

Example SAM Calculation:

TAM: $5B (all project management software)

Filters:

• Geographic: North America only (40% of global) = $2B
• Vertical: Focus on tech/SaaS companies (30% of market) = $600M
• Company size: 50-500 employees (suitable for our product, 50% of vertical) = $300M

SAM = $300M

Your SAM Calculation:

Starting TAM: $_

Filters applied:

1. [Filter type]: [Impact %] = $_
2. [Filter type]: [Impact %] = $_
3. [Filter type]: [Impact %] = $_

Your SAM: $_

4. Estimate Your SOM

Your realistic near-term target market:

Factors to consider:

Market Share Assumptions:

• What % of SAM can you capture in 1-3 years?
• Consider: Brand awareness, competitive intensity, resources
• Typical early-stage: 1-5% of SAM
• Growth stage: 5-15% of SAM

Resource Constraints:

• Sales team capacity (how many deals can you close?)
• Marketing budget (how many leads can you generate?)
• Product readiness (any features blocking adoption?)

Competitive Reality:

• How entrenched are competitors?
• What's your differentiation?
• How long to win market share from incumbents?

Example SOM Calculation:

SAM: $300M

Year 1 target: 0.5% of SAM (getting initial traction) = $1.5M

Year 2 target: 2% of SAM (scaling) = $6M

Year 3 target: 5% of SAM (established player) = $15M

SOM Year 1 = $1.5M

Your SOM Calculation:

SAM: $_

Year 1: % of SAM = $__

Year 2: % of SAM = $__

Year 3: % of SAM = $__

Your SOM (Year 1): $_

Justification for %:

• Sales capacity: reps × deals/year × $ ACV = $
• Marketing: leads/month × % close rate × $ ACV = $
• Other factors: ___

5. Visualize Your Market Opportunity

Create a simple visual representation:

┌─────────────────────────────────────┐
│         TAM: $___B                  │  ← Entire addressable universe
│  (Total market if 100% captured)    │
└────────────┬────────────────────────┘
             │
      ┌──────▼──────────────────┐
      │    SAM: $___M           │         ← Your realistic target
      │  (Reachable segment)    │
      └─────────┬───────────────┘
                │
         ┌──────▼────────┐
         │  SOM: $___M   │                ← Your near-term goal  
         │ (Obtainable)  │
         └───────────────┘

6. Segment Your SAM

Divide SAM into 2-3 key segments and prioritize:

Segment 1: [Name]

• Definition: [Industry / Size / Geo / Use case]
• Size: $_ (% of SAM)
• Why prioritize: [Reasons - less competition, better fit, easier to reach, etc.]
• Priority: [High / Medium / Low]

Segment 2: [Name]

• Definition:
• Size:
• Why prioritize:
• Priority:

Segment 3: [Name]

• Definition:
• Size:
• Why prioritize:
• Priority:

Initial Focus Segment: [Which segment will you target first?]

7. Validate Your Estimates

Sanity checks:

☐ Does my TAM align with industry reports?

☐ Is my SAM a reasonable subset (typically 10-40% of TAM)?

☐ Is my SOM achievable given current team/budget?

☐ Have I documented all assumptions clearly?

☐ Could I defend these numbers to an investor or executive?

Peer review: Share your calculations with sales, product, or finance colleagues. Ask:

• Does the customer count seem realistic?
• Are we being too optimistic or pessimistic?
• What did we miss?

Deliverable

Create a Market Sizing Document (2-3 pages) including:

1. TAM calculation with sources and methodology
2. SAM calculation with filters and rationale
3. SOM estimate with justification
4. Visual representation (concentric circles or funnel)
5. SAM segmentation with prioritization
6. List of assumptions and data sources

Presentation tip: Lead with SOM ("We can capture $X in Year 1"), then explain how you got there by showing SAM and TAM.

Example: Zoom's Market Sizing (Simplified)

TAM: All organizations needing video conferencing globally

• ~500M knowledge workers × $100/year average spend = $50B TAM

SAM: Organizations actively seeking cloud video solutions

• Focused on cloud-first (40% of market) = $20B
• Excluded regions with limited infrastructure (80% reachable) = $16B SAM

SOM: High-growth segments (education, healthcare, SMBs)

• Target 2% market share in first 3 years = $320M SOM

Zoom actually exceeded this by focusing on product-led growth and viral adoption during favorable conditions (pandemic).

Note: Capstone Save Point

Save your TAM/SAM/SOM assumptions for Section 1 (GTM Strategy) and Section 6 (Forecasting) of your Module 22 plan.

Outcome

You'll have a quantified view of your market opportunity that:

• Guides resource allocation decisions
• Sets realistic growth targets
• Identifies which market segments to prioritize
• Provides credible numbers for fundraising or planning

Remember: These are estimates, not prophecies. Revisit quarterly as you learn more about your actual market penetration and adjust assumptions accordingly.