LTV vs CAC: Customer Lifetime Value vs Acquisition Cost
The short answer: Customer Lifetime Value (LTV or CLV) is the total net revenue a business expects from a single customer over the entire relationship. Customer Acquisition Cost (CAC) is the fully loaded cost of winning that customer. Together they form the most important ratio in subscription and e-commerce businesses: LTV:CAC. A healthy ratio signals a scalable business; a poor ratio signals you are spending more to acquire customers than they will ever return.
| Dimension | LTV (Lifetime Value) | CAC (Acquisition Cost) |
|---|---|---|
| Definition | Expected revenue per customer over their lifetime | Total cost to acquire one new customer |
| Formula | Average order value × purchase frequency × customer lifespan | Total marketing + sales spend / new customers acquired |
| What it measures | Long-term customer value | Short-term cost efficiency |
| Ideal direction | Maximize | Minimize |
| Key benchmark | LTV > 3 × CAC | CAC payback < 12 months |
What Is Customer Lifetime Value (LTV)?
LTV estimates the cumulative profit a business earns from one customer from first purchase to churn. A common formula for subscription businesses is:
LTV = (Average Revenue Per User) / Churn Rate
For transactional businesses:
LTV = Average Order Value × Purchase Frequency × Average Customer Lifespan
LTV is only as accurate as the churn and margin figures behind it, so always use gross margin (not revenue) in a more refined model. Use the Customer Lifetime Value Calculator to compute LTV under multiple assumptions and understand which levers move the number most.
What Is Customer Acquisition Cost (CAC)?
CAC captures everything spent to acquire a new paying customer: advertising, salaries of marketing and sales staff, software, events, and agency fees. The formula is:
CAC = Total Acquisition Spend / Number of New Customers Acquired
Both figures should cover the same time period (usually a month or quarter). A common mistake is to include only ad spend and exclude salaries and tools, which significantly understates the true cost. Use the Customer Acquisition Cost (CAC) Calculator to get a fully loaded number.
The LTV:CAC Ratio
On its own, neither LTV nor CAC tells the full story. The LTV:CAC ratio puts them together:
LTV:CAC = LTV / CAC
Industry benchmarks:
- Less than 1:1 -- you lose money on every customer. Unsustainable.
- 1:1 to 3:1 -- marginal; growth is expensive and leaves little room for error.
- 3:1 -- the commonly cited SaaS benchmark for a healthy, scalable business.
- Greater than 5:1 -- potentially under-investing in growth; more spend could accelerate scale.
Use the LTV:CAC Ratio Calculator to benchmark your ratio and model how changes in churn, pricing, or marketing efficiency affect your growth trajectory.
Which Metric Should You Prioritize?
Both metrics must be tracked simultaneously -- they are two sides of the same equation. That said, emphasis shifts by business stage:
- Early stage: Focus on understanding CAC by channel so you know where to concentrate spend. A low-CAC channel with even modest LTV is a green light to scale.
- Growth stage: Focus on increasing LTV through retention improvements, upsells, and price optimization. Even a small reduction in churn substantially raises LTV.
- Scale stage: Focus on the LTV:CAC ratio and CAC payback period. Fast payback (under 12 months) means you can reinvest cash faster and grow without raising capital.
The Customer Lifetime Value Calculator, CAC Calculator, and LTV:CAC Ratio Calculator work best used together as a trio to stress-test your unit economics.
FAQ
How often should I recalculate LTV and CAC?
Monthly for fast-moving businesses, quarterly for slower-growth companies. CAC can shift rapidly when ad costs change or a sales rep leaves; LTV is more stable but should be recalculated whenever pricing, retention, or product mix changes significantly.
Should I use revenue or gross profit in the LTV formula?
Gross profit (revenue minus direct costs) gives a more accurate picture of value because it excludes variable costs of delivering the product or service. Revenue-based LTV overstates value and can lead to over-investment in acquisition.
What is CAC payback period and how does it relate to LTV:CAC?
CAC payback period is the number of months needed to recover the acquisition cost from a customer's gross profit contribution. A short payback period (under 12 months) is especially important for capital-constrained businesses because it reduces the cash needed to fund growth, even if the overall LTV:CAC ratio is strong.