LTV to CAC Calculator

Customer lifetime value (LTV) estimates total gross profit from an average customer over their relationship. A common SaaS formula: LTV ≈ (monthly ARPU × gross margin) ÷ monthly churn rate (as a decimal). LTV:CAC ratio = LTV ÷ customer acquisition cost. The ratio shows whether you earn back acquisition spend with room to spare.

A 3:1 LTV:CAC ratio is a widely cited benchmark — spend $1 to acquire, earn $3 in gross profit over life — but optimal ratio depends on payback period, growth goals, and capital cost. High churn destroys LTV linearly in this model. Enterprise businesses with low churn can support higher CAC; consumer apps need tighter economics.

Example: $45 ARPU, 75% gross margin, 3% monthly churn, $150 CAC. Monthly gross profit = $33.75. LTV ≈ $33.75 ÷ 0.03 = $1,125. LTV:CAC = 7.5× — strong if churn and CAC inputs are accurate. If churn doubles to 6%, LTV halves to ~$562 and ratio drops to 3.75×.

The formula LTV = ARPU × margin ÷ churn assumes exponential decay — average customer lifetime ≈ 1 ÷ monthly churn. At 3% monthly churn, average life ≈ 33 months. At 5% churn, average life ≈ 20 months.

Use gross profit, not revenue, in LTV:CAC. Comparing revenue LTV to CAC overstates health because service costs eat part of every dollar. This calculator applies margin to ARPU before dividing by churn.

Blended LTV across tiers can mislead. Enterprise logos with low churn and high ARPU dominate LTV; self-serve tiers with high churn drag averages down. Segment by cohort when making budget decisions.

Worked example with higher CAC: $60 ARPU, 80% margin, 2% churn, $300 CAC → monthly margin $48 → LTV $2,400 → ratio 8×. Raising CAC to $900 without improving retention cuts ratio to 2.67× — below the common 3× heuristic.

LTV:CAC ignores payback timing. A 5× ratio with 24-month payback still strains cash during rapid growth. Pair with CAC payback and runway tools.

Inputs matter more than benchmarks. Small errors in churn (especially early-stage with few customers) swing LTV dramatically. Use trailing 6–12 month cohort data when available.

Cohort charts beat static churn inputs once you have enough customers — month-1 churn on self-serve products often exceeds month-12 churn, skewing simple LTV formulas.

Expansion revenue (upsells, seat growth) raises LTV without raising CAC — net revenue retention above 100% is a strong signal that LTV:CAC improves over customer lifetime.

Capital markets affect acceptable LTV:CAC — in tight funding environments investors emphasize 3×+ with sub-12-month payback; growth markets sometimes tolerate lower ratios temporarily.

Logo churn vs revenue churn diverge when small customers cancel but large accounts expand — revenue-weighted LTV can exceed simple customer-count LTV in land-and-expand models.

Payback-weighted LTV:CAC combines both metrics — some investors want LTV:CAC above 3× and payback under 18 months simultaneously before increasing S&M spend.

Consumer subscription apps with viral loops may show improving LTV:CAC over cohort maturity — early LTV estimates from month-one churn overstate long-run LTV when product improves retention.

Negative churn (expansion exceeds losses) pushes LTV above simple churn formulas — net revenue retention above 100% means LTV models need expansion terms, not constant ARPU assumptions.

Sales-led enterprise deals with 12-month implementation delay revenue — LTV timing and payback both stretch; do not compare to self-serve SaaS benchmarks without adjusting horizons.

Discounted LTV models apply a discount rate to future gross profit — simple undiscounted LTV overstates present value when payback stretches beyond twelve months.

Document churn and margin assumptions in investor updates — LTV:CAC ratios move quickly when early cohorts are small and retention data is noisy.

Capital-efficient SaaS businesses often publish both LTV:CAC and net dollar retention together — strong retention supports higher acceptable CAC even when headline LTV:CAC looks flat quarter to quarter.

Early-stage companies with fewer than one hundred customers should label LTV:CAC as preliminary — variance is high until cohorts mature twelve to eighteen months.