liminfoSaaS Metrics Calculator
Free web tool: SaaS Metrics Calculator
MRR
$50,000,000
ARR
$600,000,000
ARPU
$250,000
Monthly Churn Rate
3.0%
LTV
$8,333,333
CAC
$500,000
LTV/CAC
16.7x
Good (3x+)
CAC Payback Period
2.0 months
Rule of 40
87.0
About SaaS Metrics Calculator
The SaaS Metrics Calculator computes all essential SaaS business health metrics from five inputs: monthly recurring revenue (MRR), total customer count, churned customers per month, new customers per month, and customer acquisition cost (CAC) spend per month. From these inputs, the tool derives MRR, ARR (MRR × 12), ARPU (MRR / customers), monthly churn rate (churned / total), customer lifetime value (LTV), CAC per new customer, LTV/CAC ratio, CAC payback period, and the Rule of 40 score.
SaaS founders, startup operators, growth managers, VCs conducting due diligence, and financial analysts use this calculator when building investor pitch decks, running monthly business reviews, analyzing unit economics, and benchmarking portfolio company performance. The nine metrics cover the four pillars of SaaS health: revenue efficiency (MRR, ARR, ARPU), retention (churn rate), unit economics (LTV, CAC, LTV/CAC), and operational efficiency (payback period, Rule of 40).
The LTV calculation uses ARPU divided by monthly churn rate: LTV = ARPU / (churned / total). If churn is zero, LTV is capped at 120 months of ARPU as a conservative upper bound. The LTV/CAC ratio is benchmarked against the 3x threshold — a ratio above 3x is highlighted in green indicating healthy unit economics; below 3x triggers a warning. The Rule of 40 adds the net growth rate and operating margin, with 40+ indicating a well-balanced SaaS business.
Key Features
- MRR and ARR calculation (ARR = MRR × 12) from monthly revenue input
- ARPU (Average Revenue Per User) = MRR / Total Customers
- Monthly churn rate as a percentage of total customer base
- LTV (Customer Lifetime Value) = ARPU / Monthly Churn Rate
- CAC (Customer Acquisition Cost) = Monthly CAC Spend / New Customers
- LTV/CAC ratio with green/red indicator benchmarked at the 3x threshold
- CAC Payback Period in months (CAC / ARPU)
- Rule of 40 score = Net Growth Rate + Operating Margin, with 40+ highlighted in green
Frequently Asked Questions
What is MRR and how is it calculated?
Monthly Recurring Revenue (MRR) is the normalized monthly revenue from all active subscriptions. In this calculator, MRR is the direct input — the total monthly subscription revenue. ARR (Annual Recurring Revenue) is computed as MRR × 12, giving the annualized revenue run rate. MRR and ARR are the most watched top-line metrics in SaaS and are used for valuation multiples.
What is a good monthly churn rate for SaaS?
For B2B SaaS targeting SMBs, monthly churn rates of 2–3% are common. Enterprise SaaS businesses often achieve below 1% monthly churn. Consumer SaaS can run 5–10% monthly. Churn rates above 3% per month compound to over 30% annual churn, which makes growth very difficult. Reducing churn by even 0.5% monthly can dramatically increase LTV and overall company value.
What does the LTV/CAC ratio tell you?
The LTV/CAC ratio measures the return on customer acquisition investment. A ratio of 3x or higher is the widely cited benchmark for a healthy SaaS business — it means each customer generates 3x the cost to acquire them. Below 3x suggests the business is spending too much to acquire customers relative to their value. Above 5x may indicate underinvestment in growth. The ratio should also be viewed alongside payback period.
What is the CAC payback period?
The CAC Payback Period measures how many months of ARPU revenue are needed to recover the cost of acquiring a customer: Payback = CAC / ARPU. For B2B SaaS, payback under 12 months is considered strong; 12–18 months is acceptable; above 18 months creates cash flow pressure. Fast payback gives you more capital to reinvest in growth without raising additional funding.
What is the Rule of 40?
The Rule of 40 is a benchmark for SaaS business health that combines growth and profitability: Rule of 40 = Growth Rate (%) + Operating Margin (%). A score of 40 or above indicates a healthy balance between growth and profitability. In this calculator, the Rule of 40 is approximated as net customer growth rate + revenue minus CAC margin. High-growth companies can have negative margins but still pass the Rule of 40 if growth is fast enough.
How is customer LTV calculated?
LTV is calculated as ARPU divided by monthly churn rate: LTV = ARPU / (Churned / Total Customers). This assumes an exponential survival model where each customer has a constant monthly probability of churning. If churn is zero (no customers left during the period), LTV is capped at 120 months of ARPU to avoid infinite values. The LTV represents the expected total revenue from a customer over their lifetime.
What is ARPU and how is it used?
ARPU (Average Revenue Per User) is MRR divided by total customer count. It measures the average monthly revenue generated per customer. ARPU is used to calculate LTV, CAC payback period, and to segment customers by revenue tier. Rising ARPU over time indicates successful upselling or pricing power; falling ARPU may signal a shift toward lower-value customer segments.
Can I use this calculator for annual subscription SaaS?
Yes, but normalize your inputs to monthly figures first. If customers pay annually, divide total contract value by 12 for monthly revenue. For churn, count customers whose annual contracts were not renewed in the month. CAC spend should also be the monthly marketing and sales spend, not the full annual budget. The calculator works with any recurring revenue model as long as all inputs are on a consistent monthly basis.