TAM/SAM/SOM market sizer for startup founders
Estimate market size with a TAM SAM SOM calculator. Use both top-down and bottom-up methods to create investor-ready market sizing assumptions you can defend.
Total market clarity
Define TAM, SAM, and SOM to show the full opportunity.
Investor alignment
Explain your market sizing assumptions with clear percentages.
GTM focus
Compare top-down and bottom-up sizing to validate growth plans.
Enter market sizing inputs
Use annual revenue numbers. Percentages should be realistic and defendable.
Top-down market sizing
Start from total market revenue, then apply SAM and SOM percentages.
Bottom-up market sizing
Start from target accounts and ARPA to validate your go-to-market plan.
Founder tip
TAM SAM SOM is most useful when your assumptions are explicit. Investors care more about your logic than a huge number.
Market sizing snapshot
Compare top-down and bottom-up market sizing in one view.
Top-down SOM
$40,000,000
SAM: $400,000,000 (20.0%)
Bottom-up SOM
$11,520,000
SOM accounts: 960
SOM comparison
0.29x
Bottom-up vs top-down SOM
Share this model
Links include your inputs so your team sees the same market sizing assumptions.
TAM, SAM, SOM definitions
TAM (total addressable market) is the total revenue opportunity. SAM (serviceable addressable market) is the slice you can actually serve. SOM (serviceable obtainable market) is the portion you can win in your go-to-market horizon.
TAM
Total market demand for your category.
SAM
Customers you can reach with your product and region.
SOM
Customers you can realistically acquire short-term.
Use both top-down and bottom-up market sizing for a credible TAM SAM SOM story in decks and GTM plans.
Why this matters
Market sizing is how you prioritize segments, decide whether a niche is big enough, and communicate upside to investors. It also keeps your GTM plan grounded in reality.
Keyword tip for SEO
Investors and founders often search for "TAM SAM SOM calculator", "market sizing tool", and "startup market sizing" when building decks.
FAQs
What is TAM, SAM, and SOM?
TAM is the total addressable market, SAM is the serviceable addressable market, and SOM is the serviceable obtainable market you can realistically win.
Why do investors ask for TAM/SAM/SOM?
Market sizing shows the upside potential and whether your business can scale to venture-level outcomes.
Top-down or bottom-up market sizing?
Use top-down to validate the size of the market and bottom-up to validate your go-to-market and revenue plan.
Is my data stored?
No. All calculations run locally in your browser and nothing is stored on the server.