Unit economics measures the profitability of a single "unit" of your business — most commonly one customer — by comparing the revenue that customer generates against the cost of acquiring and serving them. Positive unit economics are the foundation of a scalable, venture-backable business.
The core metrics
- Customer Acquisition Cost (CAC): the total sales and marketing spend required to acquire one new customer
- Lifetime Value (LTV): the total gross profit a customer generates over their entire relationship with the company
- LTV:CAC ratio: the gold standard metric — ideally 3:1 or higher
- CAC payback period: the number of months it takes to recoup the cost of acquiring a customer
Calculating CAC and LTV
CAC = Total sales & marketing spend in a period ÷ Number of new customers acquired
LTV = Average revenue per customer per month × Gross margin % × Average customer lifespan in months
For example, a SaaS company with $200/month ARPU, 80% gross margin, and an average customer lifespan of 30 months has an LTV of $200 × 0.8 × 30 = $4,800. If CAC is $1,200, the LTV:CAC ratio is 4:1 — healthy.
2026 benchmarks for B2B SaaS
- LTV:CAC ratio: 3:1 is good, 5:1+ is excellent (but may signal under-investment in growth)
- CAC payback period: under 12 months is the Series A bar; under 6 months is exceptional
- Gross margin: 70–85% for software, 40–60% for marketplaces, 20–40% for hardware or managed services
Why unit economics determine fundability
Investors use unit economics to answer a simple question: if we pour more money into this machine, does it produce more profit? A startup with an LTV:CAC of 1.5:1 needs to improve its economics before scaling — more capital will simply accelerate losses.
Common pitfalls
- Blended CAC — mixing organic and paid acquisition, which masks the true cost of paid channels
- Ignoring churn in LTV — assuming customers stay forever when calculating lifetime value
- Excluding all costs — CAC should include sales salaries, tools, and overhead, not just ad spend
- Cohort confusion — unit economics should be calculated by cohort, since early adopters often behave differently than later customers