The viral coefficient (K) is the average number of new users each existing user brings in. It seems like a small number, but there's a critical threshold at K=1 where behavior changes dramatically.
K-Factor Components
How many invites/shares each user sends on average
What % of invited people actually sign up
Growth Simulation
How long each viral cycle takes
What % of users leave each month
User Growth Over 6 Months
The math
Why K=1 is the magic number
Each generation is smaller. Growth requires constant paid acquisition.
Each user replaces themselves. Steady but not explosive growth.
Each generation is larger. True viral growth. Rare and powerful.
The difference between K=0.9 and K=1.1 seems tiny—just 0.2. But over multiple cycles, it's the difference between your product dying and taking over the world.