The SaaS Metrics & Rule of 40 Calculator evaluates operational health and financial performance for subscription businesses and SaaS enterprises.

### Core Venture Metric Formulas - Annual Recurring Revenue (ARR): Evaluated directly as $$\text{ARR} = \text{MRR} \times 12$$. - Rule of 40 Benchmark: Measures capital efficiency by combining top-line expansion with operating profitability: $$\text{Rule of 40 Score} = \text{Annual Revenue Growth Rate (\%)} + \text{Free Cash Flow Margin (\%)}$$ A score of 40% or higher indicates elite venture-scale financial performance. - Customer Lifespan & LTV: Evaluated from monthly churn rate ($$\text{Lifespan} = 1 / \text{Churn Rate}$$) and account revenue ($$\text{LTV} = \text{ARPU} \times \text{Lifespan}$$). - LTV-to-CAC & Payback: Evaluates marketing efficiency: $$\text{LTV:CAC Ratio} = \frac{\text{LTV}}{\text{CAC}}$$ $$\text{CAC Payback Period (Months)} = \frac{\text{CAC}}{\text{ARPU}}$$

### Worked Numeric Example - Monthly Recurring Revenue (MRR): $35,000 ($420,000 ARR) - Annual Revenue Growth Rate: 65% - Free Cash Flow Margin: -15% - Average Revenue Per Account (ARPU): $120/month - Monthly Customer Churn: 2.5% - Customer Acquisition Cost (CAC): $450 - Venture Results: - Rule of 40 Score: $65\% + (-15\%) = 50.0\%$ (Exceeds 40% threshold) - Customer Lifespan: $1 / 0.025 = 40.0\text{ months}$ - Customer Lifetime Value (LTV): $120 \times 40 = $4,800 - LTV-to-CAC Ratio: $4,800 / $450 = 10.7\times$ - CAC Payback Period: $450 / $120 = 3.8\text{ months}$

### Private Local Execution All business metrics, growth rates, and financial variables calculate entirely inside your web browser with zero remote data collection.