Measure the two metrics every SaaS investor checks: CAC payback period (months to recover customer acquisition cost) and the LTV:CAC ratio. Enter your CAC, revenue per account, gross margin, and churn to see if your unit economics actually work.
SaaS unit economics
CAC payback period is the number of months it takes to earn back what you spent acquiring a customer, measured in gross profit (not raw revenue). It's calculated as CAC ÷ (monthly revenue per account × gross margin). The faster you recover CAC, the less working capital your growth consumes. Top SaaS companies target a payback under 12 months; under 6 is elite, and over 18–24 months strains cash flow.
The LTV:CAC ratio compares the lifetime gross profit of a customer to the cost of acquiring them. Lifetime value is (monthly gross profit ÷ monthly churn), because the inverse of churn is the average customer lifespan. A healthy SaaS business runs an LTV:CAC of 3:1 or higher — below that you're overpaying for growth, and far above 5:1 often means you're underinvesting in sales and could grow faster. This calculator computes both, plus your customer lifespan and monthly gross profit, so you can see exactly where your unit economics stand.
Recover CAC in under a year to keep growth cash-efficient. Under 6 months is best-in-class.
Three dollars of lifetime gross profit per dollar of CAC is the classic benchmark for healthy SaaS.
Lifetime value is gross profit ÷ churn. Cutting churn is the fastest way to lift LTV and the ratio.
Always base payback and LTV on gross profit, not revenue — margin is what actually funds growth.
Every U.S. SaaS founder and growth marketer eventually searches "CAC payback period," "LTV to CAC ratio," and "good CAC payback for SaaS" — because investors live by these numbers. CAC payback is how many months of gross profit it takes to recover the cost of acquiring a customer, and the LTV:CAC ratio compares a customer's lifetime value to that cost. Together they reveal whether your growth is efficient or burning cash. This calculator computes both instantly.
The U.S. SaaS standard is a CAC payback under 12 months and an LTV:CAC of 3:1 or higher. A ratio under 1 means you lose money on every customer; far above 5:1 often means you are under-investing in growth. Because lifetime value is gross profit divided by churn, lowering churn is usually the fastest lever — model it above.
A SaaS startup spends $1,200 to acquire a customer paying $120/month at an 80% gross margin and 2% monthly churn. Monthly gross profit is $96, so CAC is recovered in 12.5 months. Lifetime value is about $4,800, an LTV:CAC of 4:1 — healthy unit economics that signal it is safe to scale acquisition spend.
SaaS founders, growth and demand-generation marketers, RevOps teams, and venture investors measuring unit economics, CAC payback, and the LTV:CAC ratio for subscription businesses.
Customer acquisition cost payback measures how many months of gross profit it takes to recover what you spent winning a customer. It is a cash-flow metric rather than a profitability one, and for subscription businesses it is often more binding than the better-known LTV:CAC ratio — a business can have excellent lifetime economics and still run out of money if payback takes two years, because growth consumes cash before it produces any. The critical refinement is using gross profit rather than revenue: a customer paying $175 a month at 85% gross margin only contributes $148.75 toward recovering their acquisition cost.
CAC = Total sales and marketing spend ÷ New customers acquiredCAC payback (months) = CAC ÷ (Monthly revenue per customer × Gross margin)LTV = (Monthly gross profit ÷ Monthly churn rate)LTV:CAC — 3:1 is the conventional benchmarkwhere:
Assumptions: Blended CAC mixes organic and paid acquisition and flatters the result; paid CAC is the figure that governs whether spending more actually scales. Under 12 months payback is generally healthy for SaaS, and under 6 is strong.
Compute payback on gross profit, then check lifetime value against it.
Result8.1 months to payback — LTV:CAC of 6.2:1
Both metrics are healthy, but they can disagree. Using revenue instead of gross profit would have shown 6.9 months, understating the true payback by more than a month. The cash implication is concrete: acquiring 150 customers a quarter ties up $180,000 for eight months before it returns, which is the working-capital requirement growth actually imposes.