The LTV:CAC Ratio: The Only Number That Tells If Your Business Will Survive
Key takeaways
Based on Chapter 4 of The Two Numbers
- A 3:1 LTV:CAC ratio is the healthy benchmark for most SaaS.
- Below 1:1 means you're losing money on every customer acquired.
- Segment-level ratios (by channel, plan, region) reveal hidden problems.
- The ratio shifts month to month — track it, don't snapshot it.
Quick Answer: The LTV:CAC ratio compares Customer Lifetime Value to Customer Acquisition Cost. A healthy ratio is between 3:1 and 5:1. Below 3:1 is risky; above 5:1 may mean underinvestment in growth. But the ratio alone can be misleading — payback period matters equally. A 4:1 ratio with 24-month payback can still kill your company. Lech Kaniuk details the complete framework in "The Two Numbers That Build or Break Every Business."
What Is the LTV:CAC Ratio?
The LTV:CAC ratio is the single most important metric for understanding whether your business model works. Across the companies I've built and scaled, it was the one number I checked before every growth decision.
Formula: LTV ÷ CAC = Ratio
If your Customer Lifetime Value is €300 and your Customer Acquisition Cost is €100, your ratio is 3:1. For every €1 you invest in acquiring a customer, you generate €3 in gross profit over their lifetime.
The Ratio Zones
Below 1:1
You're destroying value. Every customer costs more than they return.
1:1 to 3:1
Fragile. You might survive, but you're dependent on everything going right.
3:1 to 5:1
Healthy. Sustainable growth is possible. Most successful companies operate here.
Above 5:1
Very efficient. But ask yourself: are you underinvesting in growth?
Why a "Good" Ratio Can Still Kill You
Here's what the ratio doesn't tell you:
Payback period.
A 4:1 ratio with 24-month payback means you need deep pockets. A 3:1 ratio with 6-month payback is often more valuable.
Channel variation.
Your blended ratio might be 3:1, but one channel could be 5:1 while another is 0.8:1. Averages hide the truth.
Calculation errors.
Most companies underestimate CAC (by excluding salaries, tools, overhead) and overestimate LTV (by using revenue instead of margin).
Benchmarks by Business Model
SaaS
3:1 to 5:1 is standard. Enterprise SaaS with low churn can sustain 4:1 to 7:1.
E-commerce
Often lower (2:1 to 3:1) due to higher churn and competition.
B2B Services
Can be higher (4:1 to 6:1) when retention is strong.
Marketplaces
Varies dramatically by take rate and frequency.
Related
Go Deeper
This post covers the basics. "The Two Numbers That Build or Break Every Business" by Lech Kaniuk includes:
- The complete calculation methodology for accurate LTV and CAC
- The LTV-CAC Growth Map — a diagnostic framework beyond simple ratios
- Detailed benchmarks with context for each business model
- Case studies showing how companies improved from 2.4:1 to 4.1:1
- The payback period analysis most companies skip
This article draws on Chapter 4 of The Two Numbers, which covers combining LTV and CAC, segment-level ratios, and the payback overlay in full detail.
Next step
Check your ratio
Plug in your LTV and CAC for an instant ratio with healthy / risky benchmarks.
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Written by Lech Kaniuk, author of "The Two Numbers That Build or Break Every Business."