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SaaS Unit Economics & CAC / LTV Calculator

Calculate Customer Lifetime Value (LTV), Customer Acquisition Cost (CAC), Payback Period, and Rule of 40 score for SaaS businesses.

📊SaaS Unit Economics & CAC / LTV Analyzer

Calculate Customer Lifetime Value (LTV), Customer Acquisition Cost (CAC), Payback Period, and Rule of 40 for subscription businesses.

LTV Formula: LTV = (Monthly ARPU × Gross Margin %) ÷ Monthly Churn Rate %
CAC Formula: CAC = Monthly S&M Spend ÷ New Customers Acquired
CAC Payback (Months): Payback = CAC ÷ (Monthly ARPU × Gross Margin %)
Rule of 40: Rule of 40 = YoY Revenue Growth % + Net Profit (or FCF) Margin %

* Benchmark thresholds (3x–5x LTV:CAC, <12 month payback, ≥40% Rule of 40) are widely cited B2B SaaS industry rules of thumb (Bessemer Venture Partners / OpenView SaaS Benchmarks).

Customer Lifetime Value (LTV)

$4,800

~40.0 mo lifespan

Customer Acquisition Cost (CAC)

$500

per customer acquired

LTV : CAC Ratio

9.60x

High ROI / Under-investing (>5x)

CAC Payback Period

4.2 mo

✓ Under 12 mo (Healthy)

1. Unit Economics & Churn

$150/mo
2.5%
80%

2. Sales & Acquisition Spend

$25,000/mo
50 customers
50% ✓ Passed

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What is the SaaS Unit Economics & CAC / LTV Calculator?

The SaaS Unit Economics Calculator models vital subscription business metrics including Customer Lifetime Value (LTV), Customer Acquisition Cost (CAC), LTV:CAC efficiency ratio, CAC Payback Period (months), and Rule of 40 benchmark performance.

Who is the SaaS Unit Economics & CAC / LTV Calculator for?

Built for SaaS founders, startup CFOs, product managers, and venture capital analysts evaluating subscription business model health.

How to Use the SaaS Unit Economics & CAC / LTV Calculator

  1. Enter your Average Revenue Per User (monthly ARPU) and gross margin percentage.
  2. Input monthly customer churn rate and marketing acquisition spend.
  3. Review your LTV:CAC ratio and CAC Payback Period.
  4. Test growth and profit margins to check your Rule of 40 score.

Worked Calculation Example

A SaaS company with $150 ARPU, 2.5% monthly churn, and 80% gross margin achieves a $4,800 LTV. With $500 CAC, the LTV:CAC ratio is 9.6x with a 4.2 month payback period.

Frequently Asked Questions

What is the formula for SaaS LTV (Customer Lifetime Value)?

LTV is calculated as: LTV = (ARPU × Gross Margin %) / Monthly Churn Rate. Note that linear churn assumes constant retention and does not account for expansion revenue or negative net churn.

What is the formula for CAC Payback Period?

CAC Payback Period (in months) = CAC / (Monthly ARPU × Gross Margin %). For SMB SaaS, under 12 months is considered healthy; enterprise SaaS often targets 12–18 months.

What is the Rule of 40 and how is it calculated?

The Rule of 40 states that a healthy software company's Year-over-Year Revenue Growth Rate (%) plus its Profit Margin (%) should meet or exceed 40%.

What is an ideal SaaS LTV to CAC ratio?

A healthy SaaS benchmark is 3x to 5x. An LTV:CAC ratio below 1x loses money, while a ratio above 5x often indicates you are under-investing in marketing and leaving growth on the table.

What is the SaaS Rule of 40?

The Rule of 40 states that a SaaS company's year-over-year revenue growth rate plus its profit margin should equal or exceed 40% to be considered financially elite.

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