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Analytics & Event Tracking
K-Factor Calculator
Calculate viral growth coefficient (k-factor), project exponential growth, and get actionable insights to achieve virality.
K-Factor Inputs
Average invites sent per existing user
% of invited users who convert
1.00
K-Factor (Viral Coefficient)
Stable Growth
Formula
i × c = k
5 × 0.20 = 1.00
Growth Type
Linear
Constant new users
Viral Cycle
7 days
Time for invites to convert
Growth Projection
| Cycle | New Users | Total Users | Cumulative | Growth |
|---|---|---|---|---|
| Start | 100 | 100 | 100 | |
| Cycle 1 | 100 | 200 | 200 | +100.0% |
| Cycle 2 | 100 | 300 | 300 | +50.0% |
| Cycle 3 | 100 | 400 | 400 | +33.3% |
| Cycle 4 | 100 | 500 | 500 | +25.0% |
| Cycle 5 | 100 | 600 | 600 | +20.0% |
| Cycle 6 | 100 | 700 | 700 | +16.7% |
Time to Target
693
days to reach 10,000 users
Virality Insights
You have achieved stable growth at the break-even point (k = 1).
Small improvements to invitations or conversion will make your product viral.
Understanding K-Factor
What is K-Factor?
- • K-Factor measures viral growth coefficient
- • Formula: k = invitations × conversion rate
- • k < 1: Each user brings in fewer than 1 new user (decaying)
- • k = 1: Each user brings in exactly 1 new user (stable)
- • k > 1: Each user brings in more than 1 new user (viral)
Famous Examples
- • Hotmail: k ≈ 1.5 (viral email signatures)
- • Dropbox: k ≈ 1.3 (referral program)
- • PayPal: k ≈ 1.2 ($10 referral bonus)
- • Instagram: k ≈ 1.4 (social sharing)
- • Most viral products: k between 1.15-1.5
Learn More in The Course
This tool is derived from Module 1 of "The Ultimate Growth Engineering Course." Learn the complete experimentation framework, how to design better tests, and interpret results like a pro.
Explore the Course