Lifetime Value (LTV) vs Unit Economics

Definition

Lifetime Value is the total revenue you can expect from a single customer over the entire duration of your relationship. It is the most critical number for understanding how much you can afford to spend on acquiring customers. The simplest formula: LTV = ARPU ÷ Monthly Churn Rate. A customer paying $100/month with 5% monthly churn has an LTV of $2,000. Netflix's LTV exceeds $1,200 per subscriber because churn is below 2.5% — this justifies their $17B+ annual content spend. LTV is the roof of your building: it determines the maximum CAC you can afford, the features you can build, and the team you can hire.

Common trap

Most founders massively overestimate LTV by assuming customers will stay forever. In reality, early-stage startups have limited cohort data. A startup with 6 months of history claiming $3,000 LTV is extrapolating a trend that hasn't been validated. Use conservative estimates (12-24 months cap) until you have 3+ cohorts with 12+ months of data. Also, LTV should be calculated on gross margin, not revenue — a $2,000 LTV with 50% gross margin means only $1,000 in actual profit to cover acquisition costs.

Practical use

Calculate LTV two ways: (1) Simple: ARPU ÷ Monthly Churn Rate. (2) Cohort-based: track actual revenue from each monthly cohort over time. Compare them — if your cohort LTV is lower than your formula LTV, your churn rate is misleading you (possibly due to early-life churn spikes). Always report Gross Margin-adjusted LTV: LTV × Gross Margin. This is the number that matters for unit economics.

Formula

Definition

Unit economics is the direct revenue and costs associated with a single 'unit' of your business model (usually one customer). If your unit economics are positive, every new customer generates profit. If negative, every new customer accelerates your death. The core calculation: Unit Profit = (LTV × Gross Margin) − CAC. If LTV is $2,000, gross margin is 80%, and CAC is $1,200, unit profit is ($2,000 × 0.80) − $1,200 = $400 per customer. This means each customer eventually contributes $400 toward covering fixed costs and generating profit.

Common trap

Founders often achieve 'positive unit economics' by excluding fixed costs entirely or misclassifying variable costs. True unit economics must include a fair allocation of all variable costs. The second trap: assuming unit economics stay constant as you scale. They can improve (economies of scale in hosting, support) or worsen (higher CAC from market saturation, more support tickets from less-sophisticated users). Track unit economics by cohort and by scale.

Practical use

Calculate profit per unit: (LTV × Gross Margin) − CAC. If this number is negative, do NOT scale. Fix your pricing, reduce CAC, or improve retention first. Scaling negative unit economics is like pouring gasoline on a fire — you burn faster. Once positive, track the 'contribution margin ratio': Unit Profit ÷ Revenue per Customer. This tells you what percentage of each revenue dollar covers fixed costs.

Formula