Definition
LTV/CAC is the most important SaaS unit economics metric. A ratio below 1x means you lose money on every customer. Top SaaS companies achieve 5-10x. GitDealFlow tracks the engineering teams building products that drive retention (LTV) and viral growth (reducing CAC).
How it works in practice
LTV (customer lifetime value) is the gross profit a customer generates over their entire relationship; CAC (customer acquisition cost) is the fully loaded cost of acquiring them. The ratio LTV:CAC is the standard test of unit economics: a ratio below 1x means the company loses money on every customer it signs, regardless of how fast it grows.
LTV is usually estimated as average revenue per account times gross margin divided by the churn rate. CAC should include every cost that goes into acquiring customers, sales compensation, marketing spend, tools, and the portion of overhead that scales with acquisition. Both sides need honest definitions: underestimating churn inflates LTV, and excluding costs deflates CAC, and either one can turn a bad model into a good-looking spreadsheet.
Ratios are only meaningful relative to a company's stage and sales model. A young company with a 2x ratio may be fine if the trend is improving; a mature company with a falling ratio has a structural problem. Since LTV and CAC are private financials, investors often triangulate with public signals, GitDealFlow tracks commit velocity, contributor growth, and repository expansion across 350+ startups, a leading view of product velocity that ultimately drives retention.
Key points
- LTV = average revenue per account times gross margin divided by churn; CAC = fully loaded acquisition cost.
- Below 1x LTV:CAC means every customer destroys value.
- Honest definitions matter: churn and cost definitions decide the outcome.
- The ratio must trend, not just print: stage and trajectory decide interpretation.
- Product velocity, which drives retention, is visible publicly before financials are.
Frequently Asked Questions
What's a good LTV/CAC ratio?
3x is the minimum for a healthy SaaS business. 5x+ is excellent. Below 3x means your unit economics need work before scaling.
How is LTV calculated?
The common formula is average revenue per customer per period times gross margin, divided by the customer churn rate for that period. For example, $1,000 annual revenue per customer, 70% gross margin, and 10% annual churn gives roughly $7,000 in lifetime value. The estimate is only as good as the churn assumption, which is why cohort-based churn beats a single average.
How is CAC calculated?
Add up all costs that exist to acquire customers, sales compensation, marketing spend, advertising, tools, and the acquisition-related share of overhead, over a period, and divide by the number of new customers gained in that period. The key discipline is being complete: excluding salaries or tooling flatters the number, and a flattered CAC hides a broken payback model.
How does churn affect LTV?
Directly and non-linearly: LTV divides by churn, so a small improvement in retention produces a large jump in lifetime value. Cutting annual churn from 15% to 10% raises LTV by half. That is why investors scrutinize retention curves before they trust any LTV number in a pitch.