📊 Business Model and Inputs
Business Model
Customer Acquisition Costs (Monthly)
Include salaries, commissions, and software tools
Revenue and Retention (SaaS)
LTV : CAC Ratio
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Enter your numbers above
Customer Acquisition Cost
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Lifetime Value (LTV)
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CAC Payback Period
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📖 Key Terms Explained
Customer Acquisition Cost (CAC) The total cost - marketing plus sales - to acquire one new paying customer during a given period. Formula: (Marketing Spend + Sales Spend) / New Customers.
Lifetime Value (LTV / CLV) The gross profit a business expects to earn from a customer over the entire relationship. It accounts for gross margin, not just revenue, so it reflects real contribution to the business.
LTV:CAC Ratio The gold standard startup efficiency metric. A ratio of 3:1 or higher indicates healthy unit economics. Below 1:1 means the business is losing money on every customer acquired.
Churn Rate The percentage of subscribers who cancel each month. A 5% monthly churn means customers stay for an average of 20 months. Lower churn dramatically extends LTV.
ARPU (Avg Revenue Per User) The average monthly recurring revenue per active subscriber. Used in the SaaS LTV formula alongside gross margin and churn to determine contribution per customer.
Average Order Value (AOV) The average dollar amount spent per transaction in a retail or e-commerce context. Raising AOV through bundles or upsells is one of the fastest ways to improve retail LTV.
Gross Margin Revenue minus direct cost of goods or service delivery, expressed as a percentage. SaaS businesses typically run 70 to 90% gross margins; retail is often 30 to 60%.
Payback Period How many months it takes for the gross profit generated by a customer to repay their CAC. Shorter paybacks mean faster reinvestment of capital and stronger cash flow.

The Complete Guide to CAC, LTV, and Unit Economics

Unit economics are the foundation of every venture-fundable business. Before scaling acquisition spend, founders and operators need to know exactly how much it costs to acquire a customer, how much that customer is worth over time, and how long it takes to get that money back. This calculator handles both SaaS and retail models in real time.

How to Use This Calculator

Start by selecting your business model using the toggle at the top. Then fill in your monthly acquisition spend and the number of new customers you brought in during that same period. Next, enter your revenue and retention metrics. For SaaS, you need your monthly ARPU, gross margin, and monthly churn rate. For retail, you need average order value, gross margin, purchase frequency, and estimated customer lifespan. All outputs update instantly as you type - no calculate button is required.

How CAC Is Calculated

CAC equals the sum of all sales and marketing spend in a period divided by the number of new customers acquired in that same period. The most important discipline here is completeness: include every cost that goes into acquiring customers, including AE and SDR salaries, commissions, ad spend, software tools (CRM, outreach platforms), and trade shows. Forgetting fully-loaded sales costs is the most common reason CAC appears lower than it truly is.

How LTV Is Calculated for SaaS

The SaaS LTV formula is: (ARPU multiplied by Gross Margin percentage) divided by Monthly Churn Rate. This gives you the gross profit contribution per customer over their average lifetime. The denominator - churn rate - is what makes SaaS LTV so sensitive to retention improvements. Dropping monthly churn from 5% to 2.5% does not just double the average customer life; it doubles your LTV entirely.

How LTV Is Calculated for Retail

Retail LTV equals AOV multiplied by purchase frequency per year, multiplied by average customer lifespan in years, multiplied by gross margin percentage. Unlike SaaS, retail LTV does not assume a subscription relationship - it models expected repeat purchase behavior. Improving any of the four inputs (order value, frequency, lifespan, or margin) lifts LTV proportionally.

Interpreting the LTV:CAC Ratio

This calculator color-codes the ratio to give you an instant signal. A ratio of 3.0 or higher is shown in green and represents the benchmark most investors and operators consider healthy - enough LTV margin to cover overhead, R&D, and still generate profit. Between 1.0 and 2.9, the ratio appears in amber: the business may survive but lacks the efficiency required for aggressive growth. Below 1.0 is shown in red - every customer acquired destroys more value than they create, which is unsustainable at scale.

What Is the Payback Period and Why Does It Matter?

For SaaS businesses, the payback period is CAC divided by monthly gross profit per customer (ARPU multiplied by gross margin). It tells you how many months it takes to break even on each customer before they start generating net positive returns. A 12-month payback means your capital is tied up for a year per customer. Companies with payback periods under 12 months can reinvest cash quickly and grow with less outside funding; those above 24 months often need external capital to sustain growth.

Frequently Asked Questions

The startup gold standard is 3:1 or higher. A ratio of 3:1 means each customer generates three dollars of lifetime value for every dollar spent acquiring them, leaving enough margin to cover overhead, R&D, and growth. A ratio below 1:1 means you are losing money on every customer, which is unsustainable. Between 1:1 and 3:1 the business is borderline - it may be profitable but lacks the margin headroom most investors expect. Many high-growth SaaS companies temporarily tolerate ratios below 3:1 during aggressive expansion phases, but they must show a credible path to 3x or better.
LTV represents the contribution margin a customer delivers over their lifetime - not their raw revenue. Gross margin strips out the direct cost of serving that customer (hosting, payment processing, customer success, cost of goods sold). If you sell a $100 subscription but spend $30 delivering the service, only $70 is available to cover acquisition costs and overhead. Using gross revenue instead of gross margin overstates LTV and gives a falsely optimistic picture of unit economics. Always use margin-adjusted LTV when comparing it to CAC.
The payback period equals CAC divided by monthly gross profit per customer. You can shorten it by raising ARPU through upsells, add-ons, or pricing increases; by improving gross margin through infrastructure efficiency or renegotiating vendor contracts; or by lowering CAC through higher-converting channels, referral programs, or product-led growth that reduces reliance on paid acquisition. Annual billing plans are a powerful lever because customers who pay upfront dramatically compress the payback clock compared to monthly subscribers.
The most common mistake is forgetting fully-loaded sales costs - including AE and SDR salaries, commissions, sales tools like CRM and outreach software, and travel expenses. Another frequent error is dividing total spend by all new customers including organic and referral signups who cost almost nothing to acquire, which dramatically understates the true cost of paid acquisition. A third mistake is using a single blended CAC across all channels rather than computing channel-specific CACs, which hides the fact that some channels may be deeply unprofitable. Finally, many teams confuse period mismatches - spending this month to acquire customers who signed up last month - leading to distorted ratios.
No. All calculations run entirely in your browser using JavaScript. No numbers you enter are ever transmitted, saved, or shared with any server. Your financial data is completely private.
This calculator provides estimates for educational and planning purposes only. Results depend on the accuracy of your inputs and may not reflect actual business outcomes. Consult a financial advisor before making strategic decisions based on unit economics projections.