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Viral Coefficient (K-Factor) Calculator

Find a product or content's viral coefficient (K-factor) from invites per user and conversion rate.

Inputs

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Viral Coefficient (K)

0.500

Spark says

How it's calculated

Formula

K=Invites per User×Conversion RateK = Invites\ per\ User \times Conversion\ Rate
K
— Average number of new users each existing user brings in

What is the Viral Coefficient (K-Factor) Calculator?

The viral coefficient (K-factor) measures how many new users each existing user generates through invites — a K above 1.0 means growth is self-sustaining through virality alone (each user more than replaces themselves), while below 1.0 means virality alone won't sustain growth.

How to use it

  1. 1 Enter the average number of invites each user sends.
  2. 2 Enter what percentage of those invites convert into a new user.

Worked examples

5 invites/user, 10% conversion

K = 0.5 — each user brings in half a new user on average.

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Frequently asked questions

Is K > 1 realistic for most products?

It's rare and usually temporary — most products with K > 1 see it during a viral spike rather than sustained indefinitely; most sustainable growth combines a K below 1 with other acquisition channels.