What is Unit Economics?
Unit economics analyze the direct revenues and costs associated with a single "unit" of your business model, typically one customer. If the revenue from one customer exceeds the cost to acquire and serve them, the business model is viable. If not, growing faster just accelerates losses. Unit economics are the DNA of business model viability.
The Formula
Unit Contribution = LTV − CAC LTV:CAC Ratio = Customer Lifetime Value ÷ Customer Acquisition Cost Unit Margin = (LTV − CAC) ÷ LTV × 100
Use fully-loaded CAC and margin-adjusted LTV for the most accurate unit economics. Blended numbers mask channel-specific problems.
Worked Example
A subscription box company: $45/month price, $18 COGS per box, 8% monthly churn, $120 CAC.
- Average lifespan = 1 ÷ 0.08 = 12.5 months
- Revenue LTV = $45 × 12.5 = $562.50
- Gross margin per box = ($45 − $18) ÷ $45 = 60%
- Margin-adjusted LTV = $562.50 × 0.60 = $337.50
- Unit contribution = $337.50 − $120 = $217.50
- LTV:CAC ratio = $337.50 ÷ $120 = 2.81:1
📌 Each customer generates $217.50 in gross profit after acquisition cost. The 2.81:1 LTV:CAC is slightly below the ideal 3:1, improving retention or reducing COGS would strengthen unit economics.
Why This Matters
Business model validation
Positive unit economics prove your business model works at the individual customer level. This is the minimum bar for a viable business, everything else (growth, valuation, exit) depends on this.
Scaling confidence
If unit economics are strong, you can confidently invest in growth knowing each new customer adds value. If they're negative, scaling just means losing money faster.
Investor readiness
Investors evaluate unit economics before growth metrics. A company growing 200% YoY with negative unit economics is less fundable than one growing 50% with strong unit economics.
Common Mistakes
❌ Calculating LTV:CAC on blended data only
Overall LTV:CAC might be 4:1, but your paid acquisition channel could be 1.5:1 while organic is 10:1. Segment by channel to identify subsidization.
❌ Ignoring variable costs in LTV
Revenue LTV ignores serving costs. A $500 revenue LTV with 40% margins means only $200 is available to cover CAC. Revenue LTV overstates unit economics by 60%.
❌ Assuming static unit economics
CAC typically increases as you exhaust cheap channels. LTV can change with product improvements. Track unit economics quarterly and by customer cohort.
Industry Benchmarks
| Category | Good | Average | Poor |
|---|---|---|---|
| LTV:CAC Ratio | 3:1 to 5:1 | 2:1 to 3:1 | Below 1.5:1 |
| CAC Payback Period | 6-12 months | 12-18 months | Above 24 months |
| Gross Margin | 70%+ | 50-70% | Below 40% |
Source: a16z SaaS Metrics Guide
Benchmark data sourced from a16z SaaS Metrics Guide.