What is TAM, SAM, and SOM?

TAM (Total Addressable Market) is the total revenue opportunity if you captured 100% of the market globally. SAM (Serviceable Addressable Market) is the portion you can realistically target given your geography, customer profile, and go-to-market. SOM (Serviceable Obtainable Market) is what you can actually capture in the next 1–3 years. Series A investors typically want SOM > $10M to justify the investment thesis.

How do investors use TAM SAM SOM?

Investors use the TAM/SAM/SOM framework to assess whether a market is large enough to justify a venture-scale return. A common heuristic: TAM should be >$1B for a venture-backed company, SAM should be >$100M, and SOM should represent a credible 3-year revenue target. The most common founder mistake is presenting TAM as if it were SAM — presenting the global B2B software market when you're only serving US SMBs, for example.

What is a top-down vs bottom-up market sizing approach?

Top-down market sizing starts from the total industry size (e.g., 'the CRM market is $60B') and works down. Bottom-up market sizing starts from individual unit economics: how many buyers exist × willingness to pay × buying frequency. Bottom-up is more credible with sophisticated investors because it shows you understand your customer. This calculator uses both approaches — the industry baseline (top-down) combined with your price point and conversion assumptions (bottom-up).

Should I build a waitlist before validating my TAM?

Yes. A TAM/SAM/SOM analysis tells you the theoretical market exists — a waitlist tells you real people in that market want your specific product. The ideal sequence is: size the market (this tool) → validate demand with a waitlist → build. Even a waitlist of 200–500 qualified signups is stronger evidence than any market report when pitching investors or deciding whether to quit your job.

Free tool

TAM / SAM / SOM Calculator

Size your market for investors and sanity-check your idea before you build.

Your market parameters

Select your industry and geography, then enter your price point and realistic market capture assumptions.

Industry

Geography

Customer type

Annual price per customer

Annual revenue per customer (ACV). Used to derive customer counts — does not change TAM/SAM/SOM dollar values, which come from industry market size.

Year-1 market capture

% of SAM you expect to capture in year 1. Most startups: 0.05–0.5%.

Year-3 market capture

% of SAM you expect to reach by year 3. Series A target: SOM > $10M.

How TAM / SAM / SOM is calculated

TAM starts from published global industry estimates, adjusted for geography (e.g., North America = ~35% of global software spend) and customer type. SAM applies an industry-specific serviceable fraction — the share of the TAM your go-to-market can realistically reach. SOM multiplies SAM by your expected capture percentages for year 1 and year 3.

This is a top-down model. For investor pitches, combine it with a bottom-up calculation (number of buyers × ACV) to show two convergent estimates.

Common mistakes founders make with TAM

✗ Presenting global TAM as if it's your reachable market (it isn't).
✗ Using analyst reports without disclosing the year — market sizes date fast.
✗ Setting SOM capture at 1–5% of TAM without justifying the go-to-market to get there.
→ Pair this top-down calc with a bottom-up estimate: count your addressable buyers and multiply by ACV.
→ Validate the SOM exists with a waitlist before committing to the pitch deck numbers.

Frequently asked questions

More free tools for pre-launch founders

Ranked by what other founders use most.

View all tools →

#1 Calculator

Startup Runway Calculator

Know exactly how long your money lasts — and when to stop building and start validating.

#2 Utility

Idea Validation Scorecard

Score your startup idea across 5 dimensions and find out if it's ready to build.

#3 Data-moat

Waitlist Benchmark

Compare your waitlist's metrics against real industry data.

#4 Calculator

Referral Reward ROI Calculator

Find the break-even reward cost and ROI for each referral tier before you launch.

#5 Simulator

Waitlist Growth Simulator

Model viral waitlist growth with realistic decay, verification drop-off, and sensitivity bands.

#6 Simulator

Launch Day Forecaster (Product Hunt)

Estimate Product Hunt upvote velocity and top-3 / top-1 probability for your launch slot.

#7 Calculator

Pre-launch MRR Projector

Turn your waitlist into a revenue projection — before you've written a single line of code.

#8 Utility

llms.txt Generator

Generate a valid llms.txt file for your site so AI crawlers (ChatGPT, Claude, Perplexity) understand it.

Ready to build your waitlist?

LaunchList captures real signups — with referrals, spam protection, and analytics built in. Free for your first 100 signups.

Create your waitlist — it's free