TAM / SAM / SOM builder
Free bottom-up market size calculator with a printable summary.
Guide
Market sizing: TAM, SAM and SOM done properly
Almost every market size that fails scrutiny fails the same way: it starts from an analyst report and works down. This hub covers building the number from units instead, and defending it.
3 articles in this guide
Reading order
Work through it in sequence
Each article stands alone, but they are ordered the way the work happens on a live deal.
How to calculate TAM, SAM and SOM without inventing numbers
A practical bottom-up method for calculating TAM, SAM and SOM from unit counts and pricing, with the sanity checks investors apply and the shortcuts that get a deck rejected.
11 August 2026 · 8 min read
How do you calculate SOM?
A step-by-step method for calculating serviceable obtainable market from channel capacity and conversion rates, rather than by taking a percentage of TAM.
25 August 2026 · 6 min read
Which moats actually hold at seed stage
Most claimed moats are not moats at seed stage. A ranking of defensibility types by how quickly a funded competitor can neutralise them, with what to verify for each.
25 August 2026 · 8 min read
Free resources
Do the work, not just the reading
The same methods, packaged as tools and templates you can use on a live deal today.