Customer Lifetime Value (LTV)

Customer Lifetime Value (LTV, sometimes CLTV) is the total revenue (or gross margin, in more rigorous versions) a business expects to earn from a single customer across the entire duration of their relationship with the company. The simplest SaaS formula is: LTV = Average Revenue Per Account (ARPA) ÷ Churn Rate. If a customer pays $100/month on average and the business has 4% monthly churn (implying an average 25-month lifetime), LTV = $100 / 0.04 = $2,500. A more rigorous version multiplies by gross margin to reflect actual profit rather than topline revenue: LTV = (ARPA × Gross Margin %) / Churn Rate — since a $100/month customer costing $30/month in hosting and support infrastructure is worth less to the business than the raw revenue figure suggests. LTV is almost never useful in isolation — its entire purpose is to be compared against Customer Acquisition Cost (CAC) as the LTV\:CAC ratio, widely considered the single most important SaaS unit-economics metric. A commonly cited healthy benchmark is LTV\:CAC ≥ 3:1 (each customer is worth at least 3x what it cost to acquire them), with payback period (months to recoup CAC from gross margin) ideally under 12–18 months for venture-backed SaaS. A ratio below 1:1 means the business loses money on every customer acquired, regardless of how much revenue looks impressive on paper. Concrete worked example: a B2B SaaS spends $12,000/quarter on paid ads and content, acquiring 20 new customers that quarter — CAC = $12,000 / 20 = $600 per customer. Those customers pay $150/month average with an 80% gross margin and 2.5% monthly churn (40-month average lifetime): LTV = ($150 × 0.80) / 0.025 = $4,800. LTV\:CAC = $4,800 / $600 = 8:1 — a very healthy ratio suggesting the business could profitably spend significantly more on acquisition to grow faster. Builders track this ratio per acquisition channel (paid search vs. content vs. outbound) because CAC and resulting LTV\:CAC often vary dramatically by channel, guiding where to reinvest marketing budget. A common early-stage mistake is calculating LTV using revenue instead of gross margin, which flatters the number and can lead a founder to over-invest in paid acquisition channels that look profitable on paper but aren't once real infrastructure, support, and payment-processing costs are subtracted from every dollar of revenue collected. The simple LTV formula also assumes a constant churn rate over a customer's entire lifetime, which rarely holds in practice — churn is typically highest in a customer's first few months (customers who were never a great fit exit quickly) and drops meaningfully for customers who survive past that early window, so sophisticated LTV models increasingly use cohort-based survival curves rather than one flat churn-rate assumption to avoid systematically under- or over-estimating true lifetime value.