The two halves of unit economics. CAC is what you spend to win a customer. LTV is what they return over their lifetime. The ratio between them tells you whether the business model works.
Last updated: 2026-04-01
Total sales and marketing spend over a period, divided by the number of customers acquired in that period. The number that tells you the cost of growth.
Best as a watching metric for any business that pays to acquire customers. Useful as both a topline number and a per-channel breakdown.
The total margin a customer is expected to generate before they churn. Most teams compute it as ARPU multiplied by gross margin, divided by monthly churn rate.
Best as a planning metric. LTV sets the ceiling on what you can afford to spend acquiring a customer in any channel.
CAC = (Sales and marketing spend) / (New customers acquired)A defensible CAC includes paid media, sales salaries, BDR/SDR comp, marketing tools, and a slice of overhead. Organic-only CAC is a different metric.
LTV = (ARPU x Gross margin %) / Monthly churn rateARPU is average revenue per user per month. Gross margin reflects what's left after cost of revenue. The result is dollars of margin per customer over their lifetime.
| Criteria | CAC | LTV |
|---|---|---|
| What it measures | Cost to acquire one customer | Margin one customer returns over their lifetime |
| Time direction | Backward-looking. Reflects past spend | Forward-looking. Predicts future revenue |
| Inputs | Sales and marketing spend, new customer count | ARPU, gross margin, churn rate |
| Volatility | Low. The numerator and denominator are both observed | High. Sensitive to churn assumptions |
| Best break-down | By channel | By customer segment or plan tier |
| Healthy benchmark | Depends on LTV. Aim for LTV:CAC of 3:1 or better | No standalone benchmark. Always paired with CAC |
| Common mistake | Using only paid media spend, leaving out sales | Using revenue instead of gross margin |
| Pairs with | CAC payback period | Churn rate, retention curves |
Pros
Cons
Pros
Cons
Score your own data with both frameworks. Compare results and pick the one that fits your team.
For SaaS, 3:1 is the most cited benchmark. Anything above that points to efficient growth and anything below 3:1 points to weak unit economics. ChartMogul and First Page Sage analyses both put median B2B SaaS in the 3:1 to 5:1 range. Less than 1:1 means each customer loses money.
Gross margin. Revenue-based LTV overstates the value of each customer because it ignores the cost of serving them. For SaaS with high gross margins, the difference is small. For services-heavy or hardware-attached businesses, the gap can be large.
LTV:CAC compares total customer value to acquisition cost. CAC payback measures how many months it takes to recover CAC from gross margin alone. The general benchmark for CAC payback is 12 months or less, with median SaaS sitting closer to 20 months in recent KeyBanc and OpenView analyses.
No, and treating it as one blended number hides the answer to most growth questions. Compute it per channel: paid search, organic, partner, referral, sales-led. Blended CAC is useful for board reporting. Channel CAC is what tells you where to spend the next dollar.
Use an LTV range, not a point estimate. Compute LTV at your best, base, and worst monthly churn rates. Plan growth spend against the base case. Watch the worst case as a downside guardrail. Once churn stabilizes, tighten the range.
For early-stage businesses without enough cohort data to estimate churn confidently, CAC payback is more honest. It only requires gross margin and CAC, and it directly answers "how long until this customer is profitable". Move to LTV:CAC once you have at least 12 months of cohort retention data.