Separate TAM, SAM, and SOM assumptions
Total, serviceable, and obtainable market size each rest on different assumptions — about total population, reachable share, and realistic capture rate.
Free MVP market-sizing tool
Market Size Assumption Builder
List the specific assumptions you need to defend before you can estimate total, serviceable, and obtainable market size.
- Calculated instantly from your inputs
- No signup or data submission
- A focused next step for MVP planning
Your entries remain in this browser session and are not sent to MVPHub.
Your inputs
Turn a market claim into named assumptions
Describe the problem, geography, buyer unit, and your current pricing and confidence level.
Your calculated result
Your result
0/100
Planning score
Recommended next actions
How it works
Score evidence confidence
Your stated confidence converts into an evidence-gap score, showing how much validation work remains before the numbers are defensible.
Hand off to the calculator
Once each assumption has a real source, plug the resulting figures into the TAM-SAM-SOM Calculator for the arithmetic.
Frequently asked questions
Why separate assumptions instead of just estimating TAM directly?
A single top-down TAM number hides which specific belief is weakest. Listing assumptions lets you validate or replace the weakest one first.
What counts as a strong source for a TAM assumption?
Government census or statistics agencies, paid industry reports, trade association data, or a bottom-up calculation from known unit economics.
How is the confidence score calculated?
Your 1–5 self-rated confidence is converted to a 0–100 evidence-gap score: lower confidence produces a lower score, flagging more validation work.
Does this tool calculate my actual market size?
No — it lists the assumptions you need to validate. Use the TAM-SAM-SOM Calculator once you have real figures for each one.
What buyer unit should I use?
Pick the smallest countable unit that pays independently — a company, household, or individual user — and stay consistent across TAM, SAM, and SOM.
How we compare
| Capability | MVPHub | CB Insights | Generic AI chat assistant |
|---|---|---|---|
| Structured TAM/SAM/SOM assumption checklist | ✓ | × | — |
| Instant evidence-confidence scoring | ✓ | × | × |
| Published market and industry reports | × | ✓ | × |
| Free, no signup required | ✓ | × | — |
MVPHub generates a structured, scored assumption list from your own inputs. CB Insights sells researched market reports; a general AI assistant can draft a similar list but without a consistent scoring method or source-checklist structure.