Many SaaS businesses grow revenue quickly and go broke anyway. The reason is almost always the same: they are spending more to acquire customers than those customers are worth over their lifetime. Until unit economics are positive, growth just accelerates losses.
What LTV Means and How to Calculate It
LTV (Lifetime Value) is the total revenue a customer generates over their entire relationship with your business.
Simple LTV formula: LTV = (Average Monthly Revenue per Customer) × (Average Customer Lifetime in Months)
If customers pay $200/month on average and stay for 24 months on average, LTV = $4,800. To get gross-margin-adjusted LTV (which is more accurate), multiply by your gross margin percentage. At 80% gross margin, gross LTV = $3,840.
What CAC Means and How to Calculate It
CAC (Customer Acquisition Cost) is the total sales and marketing spend divided by the number of new customers acquired in the same period.
Example: $120,000 in sales + marketing spend in Q1, 40 new customers acquired in Q1. CAC = $3,000 per customer.
The 3:1 Ratio
The benchmark: LTV should be at least 3x CAC. At $3,840 LTV and $3,000 CAC in the example above, the LTV:CAC ratio is 1.28:1, deeply unprofitable. The business is losing money on every customer it acquires before accounting for any other operating costs.
At 3:1, there is enough margin to cover operating costs and generate profit. Above 5:1, you are probably under-investing in acquisition, leaving growth on the table. The target zone is 3:1 to 4:1 for healthy, scalable growth.
How to Improve the Ratio
Two levers: increase LTV or reduce CAC. Both are worth pursuing simultaneously, but they operate on different timelines.
- Reduce churn: Every month a customer stays adds to LTV. A 20% reduction in monthly churn can increase average customer lifetime by 25-30%.
- Expand revenue per customer: Usage-based pricing, add-ons, and higher-tier plans increase LTV without adding acquisition cost.
- Invest in channels with lower CAC: Content marketing, SEO, and referral programs typically produce lower CAC than paid acquisition at scale.
Calculate Your Ratio
Use our LTV:CAC Calculator to model your current ratio and see what changes would push you into healthy territory.
Written by Marcus Vance
Wharton MBA alumni, business strategist, and author at SuccessInformatics.