Glossary · Metrics · Updated
Unit economics describe the profitability of a single unit sold, usually one customer. They answer a simple question: when you sell one more, do you make money or lose it? While the answer is negative, growing makes the problem worse rather than solving it.
Thinking per unit separates two things the income statement mixes together: costs that vary with volume and fixed structural costs. A company can post a large loss while having excellent unit economics, if the loss comes from building the organisation rather than from the sale itself.
The reverse is far more dangerous. A company where each sale destroys value will not be saved by volume: every additional customer deepens the hole. Investors therefore look at unit economics before growth, because growth amplifies whatever is already there, in either direction.
The calculation must include every direct cost: hosting, customer support, third-party licences, payment fees. Many founders count infrastructure only and forget support, which is usually the first variable cost to bite as customer numbers rise.
Example: unit economics of one SaaS customer
The same B2B SaaS, with a €500 monthly subscription and a €3,000 CAC.
| Price paid by the customer | €500/month |
|---|---|
| Hosting and infrastructure | €40/month |
| Customer support | €45/month |
| Third-party licences and payment fees | €15/month |
| Total direct costs | €100/month |
| Contribution margin | €400/month, or 80% |
| CAC | €3,000 |
| Payback period | 7.5 months |
| Average lifetime | 50 months |
| Lifetime result per customer | €20,000 − €3,000 = €17,000 |
Each customer returns €17,000 net of acquisition cost. At that level, accelerating acquisition is the right call, even while the overall income statement stays negative because of structural costs.
The common mistake
Leaving support out of direct costs. On a product that needs hand-holding, support can be half the variable cost and turn a reported 90% margin into a real 65% one.
Frequently asked questions
How do you calculate unit economics?+
Start from one customer's revenue, subtract every direct cost they generate (infrastructure, support, licences, payment fees) to get contribution margin. Then compare that margin with acquisition cost, as a payback period and as a lifetime result.
Can you have good unit economics and still lose money?+
Yes, and that is the normal state of a growing startup. The loss then comes from structural costs and acquisition investment, not from the sale itself. That is precisely the situation a funding round exists to finance.
Related terms
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