LTV:CAC is the metric that rules them all. A 1:1 ratio means you're paying a dollar to make a dollar — that's not a business, that's a hobby. This calculator shows you the ratio, the payback period, and whether your unit economics actually support sustainable growth.
Industry benchmarks
Understanding LTV:CAC — the metric that rules them all
A 1:1 LTV:CAC ratio means you're paying a dollar to make a dollar. That's not a business, that's a hobby. Here's what the numbers actually mean.
The LTV formula
LTV = (ARPU × Gross Margin) / Monthly Churn Rate. This gives you the total gross profit you'll earn from a customer over their lifetime. The key insight: churn is the denominator. Even a small improvement in churn has an outsized impact on LTV. Going from 5% to 4% monthly churn increases LTV by 25%.
Why payback period matters more than you think
LTV:CAC ratio tells you if the math eventually works. Payback period tells you how long you need to fund the gap. A 5:1 ratio with a 36-month payback means you need deep pockets. A 3:1 ratio with an 8-month payback means you're cash-efficient and can reinvest faster.
| Payback period | Verdict | Implication |
|---|---|---|
| < 6 months | Excellent | Very capital-efficient; reinvest aggressively |
| 6–12 months | Strong | Healthy for most growth-stage SaaS |
| 12–18 months | Okay | Standard, but watch your runway |
| 18–24 months | Concerning | Requires strong retention to work |
| 24+ months | Danger zone | Unless you're enterprise with 95%+ retention |
Two levers, one ratio
You can improve LTV:CAC from either side. Most companies obsess over CAC because it's the thing that shows up on the credit card statement. But reducing churn by 1% often has a bigger impact than cutting ad spend by 20%. The smartest SaaS companies work both sides simultaneously. See how we approach both acquisition and retention.
Frequently asked
What is a good LTV:CAC ratio for SaaS?
3:1 is the textbook answer for healthy B2B SaaS. Below 3:1 means you are not generating enough margin per customer to cover overhead, R&D, and growth investment. Above 5:1 sometimes means you are underinvesting in growth and may be ceding market share to faster-moving competitors. The sweet spot is typically 3:1 to 5:1, with payback under 12 months.
How do you calculate LTV?
LTV = (ARPU x Gross Margin) / Monthly Churn Rate. ARPU is your average monthly revenue per customer. Gross margin is what is left after the cost of delivering your product (hosting, support, payment processing). Monthly churn is the percentage of customers you lose each month. Lower churn dramatically increases LTV — a 1% improvement in churn often outweighs a 20% reduction in CAC.
What is payback period and why does it matter?
Payback period is how many months it takes to recover the cost of acquiring a customer. It is calculated as CAC divided by monthly gross profit per customer. Shorter payback (under 12 months) means you are capital-efficient and can reinvest faster. Longer payback (24+ months) means you need deep pockets or strong retention to make the math work. Investors care about this because it determines how much working capital you need to fund growth.
Should I use gross margin or contribution margin?
Use gross margin (revenue minus cost of goods sold) for LTV calculations. Cost of goods sold for SaaS is typically hosting, customer support, payment processing, and any third-party software needed to deliver the product. Do not include sales and marketing — those go in CAC. Do not include R&D or G&A — those are operating expenses, not unit economics.