Draft a TAM/SAM/SOM market-sizing first pass

A structured first-pass market sizing — TAM, SAM, SOM by both top-down and bottom-up methods, as ranges — with every assumption and source laid out to interrogate.

Tuned for Gemini (Deep Research)

First

Run this in Gemini with Deep Research on, so it browses real sources rather than guessing.

The prompt

Help me size the market for [PRODUCT / CATEGORY] targeting [BUYER] in
[GEOGRAPHY]. Produce a TAM/SAM/SOM estimate using BOTH methods and reconcile them:

- Top-down: start from published industry/market-size figures. Cite each source
  and its year; prefer named research firms or filings over blog estimates.
- Bottom-up: estimate # of potential customers x realistic annual price. State
  every assumption explicitly (customer count, price, adoption %).

Then give me:
1. TAM (total), SAM (the slice you can serve), SOM (realistic 3-year capture),
   each as a range, not a single number.
2. A table of every assumption with the source or logic behind it.
3. The 3 assumptions the whole estimate is most sensitive to.
4. Anything you could NOT find a credible source for — flag it, don't invent it.

Built-in guardrail: Demands cited sources with years (research firms over blogs), an explicit assumptions table, and that anything without a credible source be flagged rather than invented.

Then

Attack the 3 most-sensitive assumptions first and replace guesses with real data, cross-check the top-down number against competitor traffic in Similarweb, kill any figure from an uncited blog, and present ranges with the assumptions table visible.

Field-tested Jul 21, 2026. If it stops working, tell us.