TAM SAM SOM Examples: 5 Real Startups Sized Step by Step

Abstract frameworks become concrete when you see the math.

42%

of startups fail because they built
something nobody wanted

Source: CB Insights

Why Examples Matter

TAM SAM SOM is easy to understand conceptually. Total market. Reachable market. Capturable market. Simple.

But sitting down to calculate your own numbers reveals the gaps in theory. What counts as "reachable"? How do you estimate "capturable"? Where do the input numbers come from?

These five examples show TAM SAM SOM applied to specific startup types. Each includes both top-down and bottom-up calculations, explains the assumptions, and highlights where founders typically go wrong.

The startups are hypothetical but realistic — based on patterns we see repeatedly in actual evaluations.

Example 1: B2B SaaS — Employee Onboarding Software

The startup: A software platform that automates employee onboarding for mid-market companies (100-1,000 employees). Monthly SaaS subscription priced at $5 per employee.

Top-Down Calculation

TAM (Total Addressable Market)

Starting point: Global HR software market is approximately $24 billion annually.

But "HR software" includes payroll, benefits, recruiting, performance management, and more. Onboarding is a subset.

HR software market: $24B
x Onboarding software portion: ~8% = $1.92B

TAM = $1.92 billion

SAM (Serviceable Addressable Market)

Applying constraints based on the business model:

Mid-market companies only (100-1,000 employees): ~35% of market = $672M
English-speaking markets (US, UK, Canada, Australia): ~55% = $370M
Companies buying standalone SaaS (vs. using HCM suites): ~60% = $222M

SAM = $222 million

SOM (Serviceable Obtainable Market)

The mid-market HR software space has established players (BambooHR, Rippling, Gusto). Realistic capture for a startup over five years:

Year 5 target: 3-4% of SAM = $7-9M ARR

SOM = $8 million (5-year)

Bottom-Up Calculation

Mid-market companies in target geographies: ~180,000
x Percentage with dedicated HR budget for tools: 40% = 72,000
x Average employees: 350
x Price per employee per year: $60

Potential SAM = 72,000 x 350 x $60 = $1.5B

This is higher than top-down. The discrepancy reveals assumptions worth investigating — either the top-down filter is too aggressive, or the bottom-up overestimates willingness to pay.

Realistic SAM after reconciliation: $300-500M

SOM (bottom-up): Capturing 200 customers at $100K ACV by year 5 = $20M ARR

What This Example Reveals

The top-down and bottom-up produce different numbers. This is normal — and valuable. The gap forces you to examine assumptions. Which estimate is more grounded? Usually the bottom-up, because it counts actual entities rather than applying filters to industry figures.

Example 2: Consumer Marketplace — Local Service Booking

The startup: A marketplace connecting homeowners with local service providers (cleaners, handymen, landscapers). Revenue model: 15% commission on transactions.

Top-Down Calculation

TAM

Starting point: Home services market in the US is approximately $600 billion annually.

But most home services happen off-platform — direct relationships, word-of-mouth, cash payments. The addressable portion is smaller.

US home services market: $600B
x Portion bookable through digital platforms: ~8% = $48B
x Commission-based revenue (15%): $7.2B

TAM = $7.2 billion (in commission revenue)

SAM

Initial markets (top 20 US metros): ~45% of digital bookings = $3.2B
Service categories supported at launch (cleaning, handyman, lawn): ~40% = $1.3B

SAM = $1.3 billion

SOM

Marketplace competition is intense (Thumbtack, Angi, TaskRabbit, plus vertical players). Network effects favor incumbents.

Realistic scenario: Achieve meaningful presence in 3-5 metros, capture 2-3% of SAM.

SOM = $30-40 million (5-year)

Bottom-Up Calculation

Households in top 20 US metros: ~35 million
x Percentage using digital platforms for home services: 15% = 5.25M
x Annual spend on bookable services: $1,200
x Take rate: 15%

SAM = 5.25M x $1,200 x 15% = $945M

Realistic customer capture (5%): 262,500 households
x Annual spend x take rate = $47M

SOM = $47 million

What This Example Reveals

Marketplace businesses have high TAMs but brutal SOM constraints. The winner-take-most dynamics of network effects mean that market share is hard to capture and harder to hold. A $7B TAM means nothing if you can't break through incumbent network effects in your initial markets.

Example 3: Mobile App — Meditation and Sleep

The startup: A subscription meditation app with personalized sleep content. Freemium model: free tier with limited content, $9.99/month premium subscription.

Top-Down Calculation

TAM

Global meditation app market: $4 billion (growing ~15% annually)

TAM = $4 billion

SAM

English-language markets: ~50% = $2B
Premium subscription segment (excluding ad-supported, one-time purchase): ~60% = $1.2B
Adults open to app-based meditation (vs. in-person, books, other methods): ~70% = $840M

SAM = $840 million

SOM

The meditation app market is dominated by Calm and Headspace, with 70%+ combined market share. Breaking into this duopoly requires significant differentiation and marketing spend.

Realistic scenario: Capture a niche (sleep-focused, specific demographic, clinical partnerships) and build to $15-25M ARR.

SOM = $20 million (5-year)

Bottom-Up Calculation

Smartphone users in English-speaking markets: ~600M
x Percentage interested in meditation apps: 8% = 48M
x Percentage willing to pay premium: 10% = 4.8M
x Annual subscription: $80 (accounting for discounts, churn)

Potential market = $384M

Realistic capture (1% of paying users): 48,000 subscribers x $80 = $3.8M ARR

This is much lower than top-down SOM. Why? The bottom-up accounts for the difficulty of converting free users to paid and competing with dominant incumbents.

SOM = $5-20M depending on execution

What This Example Reveals

Consumer app markets look large but have brutal conversion economics. The funnel from "potential users" to "paying subscribers" loses 90%+ at each stage. Bottom-up calculations that model the funnel produce more realistic SOM than top-down market share assumptions.

Example 4: B2B Services — Fractional CFO for Startups

The startup: A service providing fractional CFO support to seed and Series A startups. Pricing: $5,000-$15,000/month depending on engagement level.

Top-Down Calculation

TAM

US startups that raised seed or Series A in past 3 years: ~25,000
x Percentage that need financial leadership but can't afford full-time CFO: 60% = 15,000
x Average annual spend on fractional CFO: $80,000

TAM = 15,000 x $80K = $1.2 billion

Note: This is a much smaller TAM than software businesses. Services businesses often have natural ceilings.

SAM

Startups in tech hubs accessible to the service (SF, NYC, Austin, Boston, etc.): ~70% = $840M
Startups with enough complexity to need CFO-level support: ~50% = $420M

SAM = $420 million

SOM

This is a relationship business with high customer acquisition cost and limited scalability. Each fractional CFO can serve 4-6 clients. Growth requires recruiting more CFOs.

Realistic scenario: Build a team of 15-20 fractional CFOs serving 80 clients at $100K average engagement.

SOM = $8 million (5-year)

Bottom-Up Calculation

Seed/Series A startups needing fractional CFO: 15,000
x Percentage actively seeking this service: 20% = 3,000
x Percentage choosing a firm vs. independent contractor: 40% = 1,200
x Average engagement: $80,000

Market for firms = $96M

Realistic capture (5% of firm market): 60 clients x $80K = $4.8M

SOM = $5-8 million

What This Example Reveals

Services businesses have lower TAMs than software because they don't scale the same way. Each customer requires human delivery. SOM is constrained not just by market share but by ability to recruit and retain service providers.

Example 5: Hardware — Smart Home Security Camera

The startup: A privacy-focused home security camera with on-device AI processing (no cloud required). Price: $199 device + optional $4.99/month for cloud backup.

Airbnb Market Sizing (2024)

TAM

$1.2T

SAM

$210B

SOM

$10B

TAM — Global travel & hospitality market

SAM — Short-term rental accommodations

SOM — Realistic Year 1 market capture

Top-Down Calculation

TAM

Global home security camera market: $8 billion (devices + subscriptions)
x Smart/connected cameras: ~65% = $5.2B

TAM = $5.2 billion

SAM

North American market: ~40% = $2.1B
Privacy-conscious segment willing to pay premium: ~20% = $420M
DIY installation segment (vs. professionally installed systems): ~60% = $252M

SAM = $252 million

SOM

The market has strong incumbents (Ring, Nest, Arlo) with distribution advantages. Privacy positioning is niche but growing.

Realistic scenario: Become the leading privacy-focused option, capturing 5-8% of SAM.

SOM = $15-20 million (5-year)

Bottom-Up Calculation

US households: 130M
x Percentage interested in security cameras: 25% = 32.5M
x Percentage prioritizing privacy: 15% = 4.9M
x Percentage in buying cycle in next 5 years: 40% = 1.95M
x Average purchase (1.5 cameras + 2 years subscription): $350

Addressable opportunity = $683M

Realistic capture (2% of privacy-conscious buyers): ~40,000 households x $350 = $14M

SOM = $14-20 million

What This Example Reveals

Hardware businesses have different economics than software. Lower margins (COGS, inventory, logistics) mean you need higher revenue to achieve the same profitability. The subscription component improves LTV but requires ongoing value delivery.

Cross-Example Insights

TAM Variance by Business Model

| Business Type | TAM Range | Typical SOM/TAM Ratio | |---------------|-----------|----------------------| | B2B SaaS | $500M - $5B | 0.3% - 2% | | Consumer Marketplace | $1B - $10B | 0.2% - 1% | | Consumer App | $500M - $5B | 0.2% - 1% | | B2B Services | $100M - $1B | 0.5% - 3% | | Hardware | $500M - $10B | 0.2% - 1% |

Where Top-Down and Bottom-Up Diverge

In every example, top-down and bottom-up produced different numbers. The gaps reveal:

Filter assumptions in top-down — "8% of HR software is onboarding" is a guess
Willingness-to-pay assumptions in bottom-up — "$60/employee/year" may be optimistic
Funnel conversion assumptions — how many potential customers become actual customers?

The divergence is the point. It forces examination of assumptions that would otherwise hide in a single number. For a detailed walkthrough of how to calculate TAM SAM SOM using both methods, see our step-by-step guide.

SOM Is Where Reality Lives

Notice that SOM is dramatically smaller than TAM in every example — typically 0.5-2% of TAM. This is normal for startups.

The founders who inflate these numbers aren't lying — they're just using different assumptions. "We'll capture 5% of the market" sounds modest. But it's often 10x more aggressive than realistic given competition, resources, and execution challenges.

When it comes time to present these numbers in a pitch deck, leading with a defensible SOM matters far more than an impressive TAM.

TAM SAM SOM Example FAQs

How do you find TAM numbers? Industry reports from Gartner, IDC, Statista, IBISWorld, and McKinsey provide top-down TAM figures. For bottom-up, use census data, industry associations, and databases like LinkedIn Sales Navigator or ZoomInfo to count potential customers.

What's a good SOM for a startup? SOM of $10-50M in 5 years is typical for seed-stage startups. Less than $5M raises questions about venture viability. More than $100M requires exceptional circumstances or market timing.

Why do top-down and bottom-up calculations differ? Top-down uses industry filters (percentages of broad markets). Bottom-up counts specific customers and their spending. Different methodologies surface different assumptions — that's why using both is valuable.

What's a realistic market share assumption for SOM? First-time startups in competitive markets typically capture 1-5% of SAM in 5 years. In less competitive or emerging markets, 5-15% is possible. More than 20% requires a clear explanation of why.

Should I present the optimistic or conservative estimate? Present both with your reasoning. "SOM is $8-15M depending on competitive response" is more credible than a single point estimate. Investors expect ranges; false precision signals naivety.

How do you account for market growth in TAM SAM SOM? Use current market size for TAM, but note the growth rate. For SOM projections, you can assume you're capturing share of the future (larger) market — but be explicit about this assumption.

References

Grand View Research. Industry market size reports (various).
Statista. Market sizing data and projections.
Blank, Steve. The Four Steps to the Epiphany. K&S Ranch, 2005.
Kahneman, Daniel. Thinking, Fast and Slow. Farrar, Straus and Giroux, 2011.

Verve Intelligence calculates TAM SAM SOM for your specific idea — using bottom-up methodology, competitive analysis, and realistic assumptions that survive investor scrutiny. $99. Get your market analysis →