The Viral Coefficient (K-Factor) Calculator measures the compounding engine behind product-led growth (PLG) by tracking how many new active users are generated by each existing user through referrals, invites, and organic network effects.
Mathematical Formula
Viral Coefficient (K) = Number of Invites Sent per User * (Conversion Rate / 100)
The Law of Virality
- K > 1.0 (True Viral Explosion): Exponential word-of-mouth adoption. The user base expands automatically without paid ads (e.g., WhatsApp, Zoom, PayPal in early days).
- 0.5 < K < 1.0 (Viral Multiplier): Highly valuable flywheel. Subsidizes marketing spend by lowering effective CAC by 30% to 50%.
- K < 0.5 (Weak Virality): Acquisition remains primarily driven by outbound sales, search SEO, or paid media.
Frequently Asked Questions (FAQ)
What are the two core levers to improve the K-Factor?
Increase the number of invites sent per user (making collaboration innate to the workflow) and increase invite conversion rate (seamless one-click onboarding).
What is the role of Viral Cycle Time?
How fast a user invites others. A K of 1.1 with a 1-day cycle time explodes exponentially faster than a K of 1.1 with a 30-day cycle time.