Market Intelligence
How to Size a Market You Can Defend
Why borrowed market-size figures rarely survive scrutiny, and how to build a bottom-up model with transparent assumptions.
- Author
- Webude Research Team
- Reviewed by
- Webude Editorial
- Published
- 8 Sept 2026
- Reading time
- 11 min
Market size figures are among the most quoted and least examined numbers in business planning. A headline figure from an industry report rarely reflects the market a specific business can actually serve.
Build bottom-up
A bottom-up model starts with the number of potential customers that match your profile, multiplies by realistic adoption and pricing assumptions, and makes each assumption explicit.
Triangulate top-down
Top-down sources remain useful as a sense check. Where bottom-up and top-down estimates diverge significantly, the gap usually reveals an assumption worth investigating.
- Document every assumption and its source
- Model at least three scenarios
- Run sensitivity on the two or three variables that matter most