CAC and LTV answer the most important question in growth
The LTV:CAC ratio tells you whether your customer acquisition machine is creating value or consuming it. When LTV exceeds CAC by a sufficient margin, growth is worth accelerating. Scaling faster without that margin just compounds the loss.How each side is calculated
Customer Acquisition Cost (CAC):CAC = Total Sales and Marketing Spend / New Customers Acquired in the Same Period
All-in CAC includes salaries, commissions, tools, agency fees, and media. Blended CAC mixes new logo and expansion spend. For unit economics purposes, use new logo CAC only.
Lifetime Value (LTV):LTV = (Average Annual Contract Value × Gross Margin %) / Customer Churn Rate
| Component | Description |
|---|---|
| Average ACV | Average annual contract value across the customer base |
| Gross margin | Revenue minus cost of goods sold, expressed as a percentage |
| Churn rate | Annual customer churn rate |
Reading the gap between CAC and LTV
The ratio matters, but so does the absolute spread. The same 3:1 ratio on low CAC and low LTV points to a small addressable market per customer; on high CAC and high LTV, it signals a capital-intensive but structurally sound model. The ratio alone does not capture that difference.
The other variable to watch is payback period. You can have a strong LTV:CAC ratio but still face cash problems if it takes too long to recoup acquisition costs. A 5:1 ratio with a 36-month payback may be fine for an enterprise SaaS company with multi-year contracts and low churn, but it is a cash flow risk for a company on month-to-month billing.
Using CAC vs LTV to make investment decisions
When evaluating whether to increase marketing spend, segment CAC and LTV by channel, customer segment, and company size. The aggregate ratio can mask wide variation underneath. A channel that looks average at the blended level may be the highest-performing channel in the mix when you isolate it, or the worst.
See LTV:CAC Ratio for more on interpreting the ratio in practice, and CAC Payback Period for the time dimension of acquisition efficiency.
Frequently Asked Questions
What is a healthy LTV to CAC ratio for B2B SaaS?
A commonly cited guideline is 3:1, meaning the lifetime value is at least three times the acquisition cost. Below 3:1 suggests you are spending too much to acquire relative to what customers generate. Above a certain threshold, it can indicate underinvestment in growth. The right ratio for your business depends on your market size, competitive intensity, and growth stage.
Should LTV be calculated on revenue or gross profit?
Gross profit. Using revenue inflates LTV because it ignores the cost of serving the customer. Comparing revenue-based LTV to a fully-loaded CAC produces a false picture of unit economics. Both sides of the ratio should use consistent treatment of costs.
How does churn affect the LTV side of the ratio?
Churn is the primary driver of LTV degradation. Higher churn shortens the average customer lifetime, which compresses the revenue and margin a customer can generate. A small improvement in retention has a compounding effect on LTV because it extends the window over which each customer contributes.
Put these metrics to work
ORM builds custom revenue forecast models that turn concepts like cac vs ltv into prescriptive action for your team.
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