Understanding LTV:CAC Ratio - The North Star Metric for SaaS

What is LTV:CAC Ratio?

The LTV:CAC ratio is the relationship between the lifetime value of a customer (LTV) and the cost to acquire that customer (CAC). It's a fundamental metric that tells you whether your business model is sustainable.

**Formula:** LTV:CAC Ratio = Customer Lifetime Value ÷ Customer Acquisition Cost

Why It Matters

The Rule of 3:1

Most successful SaaS companies target an LTV:CAC ratio of at least 3:1. This means for every $1 spent on acquisition, you should get $3 back over the customer's lifetime.

**Below 1:1** - You're losing money on every customer

**1:1 to 3:1** - Survivable but inefficient

**3:1 to 5:1** - Healthy and sustainable

**Above 5:1** - Potentially under-investing in growth

Investor Perspective

VCs look at LTV:CAC to assess:

Business model viability

Scalability potential

Capital efficiency

Growth runway

How to Calculate LTV

Simple LTV Formula:

LTV = ARPU × Customer Lifetime

More Accurate:

LTV = (ARPU × Gross Margin) ÷ Monthly Churn Rate

Example Calculation

ARPU: $100/month

Gross Margin: 80%

Monthly Churn: 2.5%

LTV = ($100 × 0.80) ÷ 0.025 = $3,200

How to Calculate CAC

CAC Formula:

CAC = Total Sales & Marketing Costs ÷ New Customers Acquired

What to Include

Paid advertising

Sales team salaries & commissions

Marketing team costs

Software tools (CRM, marketing automation)

Content creation costs

Improving Your Ratio

Increase LTV

Reduce churn through better onboarding

Increase ARPU through upsells and cross-sells

Improve product value to justify price increases

Decrease CAC

Optimize ad spend efficiency

Improve conversion rates

Invest in organic/inbound channels

Shorten sales cycles

Common Mistakes

**Excluding costs from CAC** - Be comprehensive

**Using wrong timeframes** - Match periods correctly

**Ignoring cohort differences** - Segment your analysis

**Not accounting for gross margin** - Use gross profit, not revenue

Next Steps

Start tracking your LTV:CAC ratio monthly. Use Valthentic to automate calculations and visualize trends over time.