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Market Size Calculator (TAM/SAM/SOM)
Calculate Total Addressable Market, Serviceable Addressable Market, and Serviceable Obtainable Market for your pitch deck or business plan. Free, no signup.
Competition
How crowded is the space for this exact outcome?
Execution
Can a focused team ship a credible first version quickly?
Revenue path
Is there a believable way to monetize early?
Customer clarity
Do you know exactly who owns this pain day to day?
TAM/SAM/SOM sizing gets a bad name because most founders inflate it — 'the global market is $500B, if we capture just 1%...' is the fastest way to lose investor trust.
This calculator forces bottom-up sizing: start from a real buyer count and real spend per buyer, then narrow down honestly. That's the version investors actually believe.
Free calculator
Market size calculator (TAM / SAM / SOM)
Bottom-up market sizing: total buyers × annual spend, narrowed down to what you can reach and realistically win.
£/yr
%
%
Results
TAM (total market)£60.00M
SAM (serviceable)£12.00M
SOM (obtainable)£1.20M
A good number doesn't mean a good idea.
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TAM, SAM and SOM defined
TAM (Total Addressable Market) is the revenue opportunity if you captured 100% of the market — an upper bound, not a target. SAM (Serviceable Addressable Market) is the slice you can actually reach given your geography, language, and business model. SOM (Serviceable Obtainable Market) is what you could realistically win in the next 2–3 years given competition and your resources.
Bottom-up beats top-down every time
Top-down sizing starts with a huge global number and applies an arbitrary percentage. Bottom-up sizing starts with a specific buyer count (e.g. '4,200 UK accounting practices with 5–20 staff') and a realistic spend per buyer, then works up. Investors can sanity-check bottom-up numbers; they instantly discount top-down ones.
How this calculator works
- Enter the total number of potential buyers in your specific category.
- Enter what one buyer would realistically spend per year on this solution.
- Enter the percentage of that market you can actually reach (SAM).
- Enter the percentage of the reachable market you could realistically win in ~3 years (SOM).
Direct answer — Market Size Calculator (TAM/SAM/SOM)
The Skip or Ship Idea Lifecycle System evaluates ideas with five consistent signals: market demand, competition intensity, execution difficulty, revenue potential, and customer clarity. Same inputs, same verdict — every time.
What to prove first
One buyer segment with recurring pain and a clear trigger to pay now. If that is vague, validation can't fix it.
What kills momentum
Generic ICPs, vague outcomes, and zero distribution plan. These collapse execution speed within weeks.
What to decide next
One channel, one wedge use case, one pricing hypothesis to test in the next 14 days.
Stop reading. Get your verdict.
Describe your idea and the Skip or Ship engine returns a Ship, Fix, or Skip verdict with a full 10-category score breakdown — free, in 30 seconds, no signup.
Frequently asked questions
How do I calculate market size (TAM, SAM and SOM) for a startup?
Bottom-up, not top-down: count your specific potential buyers (TAM), multiply by realistic annual spend per buyer, then narrow to the share you can actually reach given geography and channel (SAM), and the share you could realistically win in 2–3 years given competition (SOM). Enter those four numbers above and the calculator does the rest.
What's a good SOM percentage for a pitch deck?
Most credible SOM estimates land between 1% and 10% of SAM within 3–5 years, depending on competition density and your distribution advantage. Anything above 20% needs an unusually strong justification.
Do investors actually care about TAM?
They care about TAM as a ceiling check — is the market even big enough to build a venture-scale business — but they weight SAM and SOM far more heavily when assessing near-term viability.
Can a small TAM still be a good business?
Yes. Many highly profitable indie businesses operate in TAMs under £50M because they own the niche completely and charge premium prices. Small TAM only matters if you need venture-scale returns.
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