Understanding SaaS Unit Economics
Unit economics measure the profitability of acquiring and serving a single customer over their lifetime. For SaaS businesses, these metrics determine whether your growth is sustainable or if you're burning cash to acquire customers who will never pay back their acquisition cost. This calculator helps you model the three core metrics: LTV:CAC ratio, CAC payback period, and net revenue retention (NRR).
By adjusting inputs like average revenue per user, churn rate, and expansion revenue, you can simulate how changes to your business model affect long-term profitability. Healthy unit economics are essential for fundraising, as investors use these metrics to evaluate whether your customer acquisition strategy is working.
How to Use This Tool
Enter Customer Revenue
Input your Average Revenue Per User (ARPU) per month. This is total recurring revenue divided by active customers.
Set Gross Margin
Enter your gross margin percentage. This excludes COGS like hosting, support costs, and payment processing.
Configure Churn & Expansion
Set monthly churn rate and expansion rate. Expansion includes upsells, cross-sells, and seat additions.
Add Acquisition Cost
Enter your Customer Acquisition Cost (CAC)—total sales and marketing spend divided by new customers acquired.
Understanding Your Inputs
ARPU (Average Revenue Per User)
Monthly recurring revenue from a single customer. Higher ARPU generally improves unit economics.
Gross Margin %
Percentage of revenue remaining after direct costs. SaaS typically runs 70-85% gross margin.
Monthly Churn Rate
Percentage of customers who cancel each month. 2-3% monthly is typical for SMB SaaS; enterprise should be under 1%.
Expansion Rate
Monthly revenue increase from existing customers through upsells or seat expansion. Helps offset churn.
CAC (Customer Acquisition Cost)
Total cost to acquire one customer, including marketing, sales salaries, and tools. Lower CAC improves payback period.
Reading Your Results
LTV (Lifetime Value)
Total gross profit from a customer over their lifetime. Calculated as: (ARPU × Gross Margin) / Churn Rate.
LTV:CAC Ratio
How much value you get per dollar spent acquiring customers. 3:1 is healthy, 5:1+ is excellent, under 1:1 means losing money.
CAC Payback Period
Months to recover acquisition cost from gross profit. Under 12 months is good; under 6 months is excellent.
Net Revenue Retention (NRR)
Revenue from existing customers after churn and expansion. 100%+ means you grow without new customers. 120%+ is elite.
LTV:CAC Ratio
Customer Lifetime Value vs. Acquisition Cost. 3:1 is good, 5:1 is excellent.
Payback Period
Months to recoup CAC from gross margin. Under 12 months is healthy.
Net Revenue Retention
Revenue from existing customers including expansion. 100%+ means growth without new sales.
Pro TipExpansion Beats Acquisition
Increasing expansion revenue is often more impactful than reducing CAC. If your expansion rate exceeds churn, you achieve "negative churn"—meaning existing customers generate more revenue over time, dramatically improving LTV without additional acquisition spending.
Unit Economics (LTV/CAC) Data
What is it?
Unit Economics measures the direct revenues and costs associated with a single unit of a business (e.g., one customer or one item sold). It determines if a business model is fundamentally profitable at a micro level.
The Formula
How to calculate: Customer Lifetime Value (LTV) ÷ Customer Acquisition Cost (CAC)
Industry Benchmarks
Frequently Asked Questions
The LTV:CAC ratio compares the total net profit a company makes from one customer over their entire relationship (Lifetime Value) against the total cost to acquire that customer (Customer Acquisition Cost). A 3:1 ratio means you make $3 for every $1 spent on marketing/sales.
The CAC Payback Period is the number of months it takes to recover the cost of acquiring a customer. It is calculated by dividing CAC by the Monthly Gross Margin per customer. For startups, a payback period under 12 months is considered excellent.