Market sizing term
TAM / SAM / SOM (market sizing)
The TAM/SAM/SOM hierarchy is the canonical market-sizing tool in startup fundraising. TAM is the size of the entire need; SAM is the segment you target; SOM is the slice you can credibly capture in your time horizon. The exercise produces a number range — useful for investors, less useful for indie SaaS operators.
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How to operationalize this
Compute SOM honestly: count namable potential customers in your ICP × average expected ARPU × realistic penetration rate (5-15% for new entrants in 3 years). The SOM number is the cap on your near-term ambition. TAM and SAM are abstractions; SOM is operational.
Common misuse
Inflating TAM to make the opportunity sound venture-grade. Indie SaaS does not need a $10B TAM; it needs a SOM of 1,000+ reachable customers paying $50/month. Inflated TAM numbers lose credibility instantly with anyone who has done the math themselves.
What “good” looks like for indie SaaS
SOM of 1,000-10,000 namable potential customers in the ICP, with average ARPU of $50-$500/month and realistic 5-15% penetration in 3 years. This produces a $30k-$1M MRR ceiling — perfectly healthy indie scale.
Frequently asked
- Do I need to do TAM/SAM/SOM analysis for indie SaaS?
- Not formally. The questions matter — how big is the addressable market, who is reachable, what penetration is realistic — but you do not need the slide. A one-paragraph back-of-envelope SOM is enough.
Apply the term to a live page
The free 90-second Launch Diagnostic labels which Brunson failure mode your page hits — many of these terms have direct connections to the diagnosis.