How to use AI for market sizing (TAM, SAM, SOM) in 30 seconds
The TAM slide you wrote is probably wrong. Here's how to make it less wrong in 30 seconds.
Daniel
Fifteen years running growth for SaaS, ecommerce, and hardware brands. Currently shipping SaaSValidatr out of Australia.
Every first-time founder's TAM slide has the same shape: 'global market for X is $Y billion, we only need 1% to be huge.' Investors have seen ten thousand versions of this and tune out the moment the number appears. The problem isn't the framework — it's that the number is unsourced, uncontested, and usually pulled from a 2018 IDC report via the fourth Google result.
Make the AI show its working
Don't ask 'what's the TAM for [X]'. Ask 'walk me through how you'd estimate the TAM for [X] bottom-up from unit economics, then cross-check it top-down from published market research.' The phrasing forces the model to expose its assumptions. Cross-check each assumption yourself. Half of them will be wrong; that's the job.
The three numbers that matter
- TAM — total addressable market, if everyone who could buy did.
- SAM — serviceable addressable market, the slice you can reach given language, geography, distribution.
- SOM — share of market, the slice you can realistically win in 3 years.
SOM is the one that gets you funded. TAM is marketing. If your SOM assumption is honest and your unit economics stack, the TAM slide becomes a footnote. If your SOM is a guess, no TAM slide saves you.
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