Unit Economics
Unit economics is the revenue, variable cost and acquisition cost attached to a single unit of a business — a customer, a transaction, an account or an order — and the profit or loss each unit produces over its life. It shows whether growth creates value or multiplies losses, before fixed costs and scale blur the answer.
- Also known as
- Per-unit economics, Customer-level economics
- Used at
- board packs and investment committees of start-ups and scale-ups, venture and growth-equity rounds, and commercial and financial due diligence on acquisitions
- Core measures
- contribution margin per unit (revenue less variable costs), customer acquisition cost (CAC), customer lifetime value (LTV) built from contribution and retention, the LTV-to-CAC ratio, and the payback period on CAC
- Typical benchmark
- an LTV-to-CAC ratio of around 3:1 is widely treated as healthy; below 1:1 each new customer destroys value
- Fintech specifics
- revenue per unit is often interchange, FX margin, net interest or a take rate on volume; variable costs include processing and scheme fees, KYC checks, fraud and credit losses, and support; in the UK and EU, caps on consumer card interchange (0.2% for debit, 0.3% for credit) limit what a card earns
- Parties
- founders and finance teams who build the model, investors and acquirers who test it
How unit economics works in practice
The work starts by choosing the unit. For a payments company it is usually the merchant or the transaction; for a neobank the funded account; for a lender the loan. Every cost is then sorted into variable, rising with each unit, or fixed. CAC is loaded honestly: paid marketing, sign-up bonuses, referral rewards, sales salaries, and the onboarding checks paid for customers who never activate.
Averages mislead, so the analysis runs by cohort: customers acquired in the same month, followed for revenue, cost and survival. A cohort chart shows whether newer customers behave like older ones, whether retention flattens or keeps falling, and when each cohort paid back its CAC. A company whose recent cohorts are weaker than its early ones is buying growth at falling returns, even while total revenue rises.
For an investor or acquirer, unit economics decides what the business is worth at scale. Positive contribution with a long payback needs capital, which shows up in the burn rate and runway; negative contribution cannot be cured by growth. Diligence rebuilds the model from transaction-level data rather than accepting the management presentation, and looks hard at blended CAC, which hides expensive paid channels behind free organic sign-ups, and at lifetime values that assume retention the cohorts have not yet shown.
Example
A consumer neobank spends £2.1m on acquisition in a quarter and gains 30,000 funded accounts: a CAC of £70. Each active account earns £4.50 a month from interchange, FX margin and subscriptions, and costs £1.90 in card processing, KYC, fraud losses, support and hosting — a contribution of £2.60 a month. Ignoring churn, payback takes 27 months. But cohort data show 40% of accounts inactive after a year and steady attrition after that, so five-year contribution per account is about £75: an LTV-to-CAC ratio of roughly 1.1:1. Management's presentation shows 7:1, using a blended CAC of £22 that counts organic sign-ups and a five-year lifetime with no churn. The buyer prices on the first figure.
Common mistakes
- Blending organic and paid acquisition into one CAC. - Calculating lifetime value from revenue instead of contribution. - Assuming retention that the cohorts have not yet demonstrated. - Leaving fraud losses, chargebacks and KYC costs out of variable cost. - Expecting scale to fix a negative contribution per unit. - Counting sign-ups as the unit when only active or funded accounts earn.