About Customer LTV:CAC Ratio Calculator
The LTV:CAC ratio is the single most important efficiency metric for subscription and SaaS businesses because it tells you, in one number, whether your growth engine is profitable or burning cash. LTV stands for Customer Lifetime Value—the total gross profit you expect to earn from one customer over their entire relationship with you. CAC stands for Customer Acquisition Cost—the total marketing and sales spend required to win that customer. When you divide LTV by CAC, you get a ratio that benchmarks the return on every dollar you invest in growth. A ratio below 1:1 means you lose money on every new customer. A ratio around 1:1 to 2:1 means you are roughly breaking even but leaving little room for overhead, product development, or unexpected churn. Most venture-backed SaaS companies aim for 3:1 or higher, and world-class businesses often operate between 5:1 and 8:1. However, a ratio above 10:1 can signal under-investment in growth. This calculator helps founders, marketers, and finance teams stress-test those numbers with their real ARPU, gross margin, monthly churn, and acquisition cost. Whether you are preparing for an investor update, reallocating ad spend, or building a financial model, understanding your LTV:CAC ratio gives you the confidence to scale predictably.
How It Works
The calculator starts with your average monthly revenue per user and strips out variable costs using your gross margin percentage. That gives you the true monthly profit contribution per customer. It then divides that figure by your monthly churn rate to estimate how much that customer is worth over their lifetime. If a customer generates $50 per month at an 80% gross margin, the monthly gross profit is $40. At a 5% monthly churn, the expected lifetime is 20 months, so the LTV is $800. The calculator then divides that LTV by your customer acquisition cost. If you spend $200 to acquire the customer, your LTV:CAC ratio is 4:1.
Formula & Calculation Logic
Customer Lifetime Value equals (Monthly ARPU × Gross Margin %) ÷ Monthly Churn Rate. The LTV:CAC Ratio equals Customer Lifetime Value ÷ Customer Acquisition Cost. ARPU captures revenue per customer; gross margin converts revenue into gross profit; churn converts monthly profit into lifetime value by estimating how long customers stay. CAC includes paid ads, sales commissions, salaries, and tools attributable to acquisition. The model assumes constant churn, constant ARPU, and stable gross margins, so it works best for mature subscription segments.
Step-by-Step Guide
- Step 1: Enter your Monthly Revenue per User (ARPU).
- Step 2: Enter your Gross Margin percentage to reflect profit after direct costs.
- Step 3: Enter your Monthly Churn Rate percentage to estimate customer lifetime.
- Step 4: Enter your Customer Acquisition Cost (CAC).
- Step 5: Review your Customer Lifetime Value and LTV:CAC Ratio.
- Step 6: Compare the ratio to the 3:1 benchmark and adjust acquisition strategy accordingly.
Example Calculations
- Scenario 1: A B2B SaaS startup has $200 ARPU, 75% gross margin, 2% monthly churn, and $1,200 CAC. LTV = $7,500 and the ratio is 6.25:1, indicating healthy unit economics.
- Scenario 2: A mobile app charges $9.99 per month, has a 60% gross margin, 8% monthly churn, and spends $90 on CAC. LTV = $74.93 and the ratio is 0.83:1, meaning acquisition is currently unprofitable.
- Scenario 3: A subscription box company earns $45 ARPU, 50% gross margin, 5% churn, and $120 CAC. LTV = $450 and the ratio is 3.75:1, showing sustainable growth potential.
Common Use Cases
- Founders preparing investor pitch decks need defensible unit economics.
- Marketing managers decide which channels deserve higher or lower budgets.
- Finance teams build annual recurring revenue and cash-flow forecasts.
- Sales leaders set quotas and commission structures that preserve margin.
- Product managers evaluate whether onboarding improvements justify CAC increases.
Pro Tips
- Segment LTV:CAC by channel—paid social may look very different from organic SEO.
- Include fully loaded CAC, not just ad spend, to avoid inflating the ratio.
- Use cohort-based churn instead of blended churn for more accurate LTV.
- A 3:1 ratio is a rule of thumb; capital-efficient businesses may target higher.
- Revisit the ratio quarterly because churn and CAC can shift quickly.
Common Mistakes to Avoid
- Ignoring gross margin and using revenue instead of profit in LTV.
- Using annual churn without converting it to a monthly rate.
- Comparing a monthly LTV to an annual CAC figure.
- Forgetting to include sales salaries, tools, and overhead in CAC.
- Treating a single LTV:CAC number as gospel without segmenting by customer type.
Why Use This Tool?
- Quantifies whether growth spending is profitable at the unit level.
- Supports better capital allocation across marketing channels.
- Gives investors a quick, standardized health check on the business.