What 3:1 actually means
For every dollar spent acquiring a customer you should expect three dollars in gross-margin lifetime value. Above 3:1 means you can press harder on growth; below means you're funding the customer rather than the company.
- • Gross margin matters — revenue LTV is vanity, contribution LTV is truth.
- • Churn is the biggest lever: small reductions compound into large LTV swings.
- • Pair this with the SaaS MRR calculator to see growth and efficiency together.
When LTV:CAC is misleading
Early-stage products don't have enough customer history to estimate churn accurately. Treat the ratio as directional in the first 6–12 months and rely more on CAC payback.
LTV:CAC is the single most-quoted SaaS metric and the most-misused. Most calculators give you a vanity number with no payback period, no margin adjustment, and no sanity check on cohort age. This one shows the full picture.
What each input means
Get these inputs right and the output is reliable. Get them wrong and the calculator just multiplies bad assumptions.
ARPU (avg revenue per user / month)
Total MRR ÷ active customers. Don't blend with one-time revenue.
Typical range: $20–80 SMB; $200–1,500 mid-market; $3k–25k enterprise.
Gross margin %
(Revenue − COGS) ÷ revenue. SaaS COGS = hosting + support + payment fees + 3rd-party APIs.
Typical range: 70–85% for healthy SaaS; <70% means margin issues to fix before scaling.
Monthly churn rate
% of customers lost each month, not annually.
Typical range: 5–8% SMB monthly; <2% mid-market; <0.5% enterprise.
Customer Acquisition Cost (CAC)
Total sales + marketing spend ÷ new customers acquired in same period.
Typical range: $200–800 SMB; $5k–25k mid-market; $50k–250k enterprise.
Worked examples
Real scenarios with the math walked through line by line.
SMB SaaS, $79/mo plan
Scenario: ARPU $79, 78% gross margin, 5% monthly churn, $400 CAC.
Math: Lifetime = 1 ÷ 0.05 = 20 months. LTV = 79 × 0.78 × 20 = $1,232. LTV:CAC = $1,232 ÷ $400 = 3.1.
Outcome: Healthy 3:1. Payback = 400 ÷ (79 × 0.78) = 6.5 months. Investable.
Mid-market SaaS, $800/mo plan
Scenario: ARPU $800, 82% gross margin, 1.5% churn, $9,000 CAC.
Math: Lifetime = 67 months. LTV = 800 × 0.82 × 67 = $43,952. Ratio = 4.9.
Outcome: Excellent. Payback = 14 months — long but defensible at this LTV. Push expansion to shorten payback.
Common mistakes
Where this calculation usually goes wrong in the real world.
- Using ARPU instead of gross profit per user. LTV before margin is fantasy revenue.
- Using annual churn divided by 12 instead of true monthly churn. They're not the same.
- Including only paid acquisition in CAC. Sales salaries, content team, demos all count.
- Calculating LTV in your first 6 months — you don't have enough cohort data yet.
When to use this calculator
- Justifying paid acquisition spend to a board.
- Prioritizing churn reduction vs CAC reduction (look at payback period to decide).
- Pricing — modeling whether a price hike is worth the conversion drop.
- Channel selection — comparing organic vs paid LTV:CAC.
Glossary
LTV
Lifetime value. Gross profit a customer generates over their full relationship.
CAC
Customer acquisition cost. Fully-loaded sales + marketing ÷ new customers.
Payback period
Months to recoup CAC from gross profit. <12 SMB, <18 mid-market, <24 enterprise.
CAC Magic Number
Net new ARR ÷ S&M spend. >1 means efficient; >1.5 means accelerate spend.
More questions answered
What's a good LTV:CAC ratio?
3:1 is the textbook minimum. Below 3 burns cash. Above 5 usually means you're under-investing in growth and could spend more aggressively.
Should I include expansion revenue in LTV?
Yes, but track both. LTV with expansion (often 30–60% higher) is real money but harder to forecast for new cohorts. Show the more conservative figure to investors.
How is LTV different from ARR?
ARR is current run-rate. LTV is forward-looking: how much one customer is worth over their full lifetime. ARR tells you 'now', LTV tells you 'unit economics'.
Related guides
Long-form playbooks on the same topic, written by the RevenueLab editorial team.
Methodology last reviewed: 2025-11 by the RevenueLab editorial team.
FAQ
What's a good LTV:CAC ratio?
3:1 is the industry benchmark. Above 5:1 may mean you're under-investing in growth. Below 1:1 means you lose money on each customer.
Should LTV use revenue or gross margin?
Always use gross margin (contribution LTV). Revenue LTV ignores cost of goods sold and overstates economics.
How do I lower CAC?
The fastest wins are usually conversion-rate optimization, organic SEO content, and referral loops — paid channels rarely get cheaper at scale.