K-Factor vs LTV:CAC
K-Factor (Viral Coefficient) and LTV:CAC (Lifetime Value to Acquisition Cost Ratio) both come up in business conversations and get confused. Here's the plain-English difference, side by side, so you can use each one with confidence.
The key difference: K-Factor refers to viral coefficient, while LTV:CAC refers to lifetime value to acquisition cost ratio — they describe different things even when they show up in the same sentence.
K-Factor — Viral Coefficient
The average number of new users each existing user brings in. A K-factor above 1.0 means true viral growth; below 1.0 means referrals supplement but don't replace paid acquisition.
LTV:CAC — Lifetime Value to Acquisition Cost Ratio
The ratio of what a customer is worth over their lifetime vs. what it cost to acquire them. Healthy SaaS benchmark is 3:1 or better — anything under 1:1 means you are paying to lose money.
When to use K-Factor
Reach for "K-Factor" when the conversation is specifically about viral coefficient. The average number of new users each existing user brings in. A K-factor above 1.0 means true viral growth; below 1.0 means referrals supplement but don't replace paid acquisition.
When to use LTV:CAC
Reach for "LTV:CAC" when the conversation is specifically about lifetime value to acquisition cost ratio. The ratio of what a customer is worth over their lifetime vs. what it cost to acquire them. Healthy SaaS benchmark is 3:1 or better — anything under 1:1 means you are paying to lose money.
FAQs
What is the difference between K-Factor and LTV:CAC?
K-Factor stands for Viral Coefficient — The average number of new users each existing user brings in. A K-factor above 1.0 means true viral growth; below 1.0 means referrals supplement but don't replace paid acquisition. LTV:CAC stands for Lifetime Value to Acquisition Cost Ratio — The ratio of what a customer is worth over their lifetime vs. what it cost to acquire them. Healthy SaaS benchmark is 3:1 or better — anything under 1:1 means you are paying to lose money.
Are K-Factor and LTV:CAC the same thing?
No. They're often used in the same conversation because they're related, but they describe different concepts. K-Factor = Viral Coefficient. LTV:CAC = Lifetime Value to Acquisition Cost Ratio.
When should I use K-Factor vs LTV:CAC?
Use K-Factor when you're specifically referring to viral coefficient. Use LTV:CAC when the topic is lifetime value to acquisition cost ratio.