How does churn affect your valuation? See if your subscription model is scaling profitably.
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The SaaS LTV to CAC Calculator is the ultimate health-check tool for any subscription-based business. Whether you are running a B2B enterprise software company or a B2C consumer app, investors and founders rely on a few core metrics to determine if the business model is sustainable. The two most important metrics are Customer Lifetime Value (LTV) and Customer Acquisition Cost (CAC).
This calculator takes your raw data—Average Revenue Per User (ARPU), Gross Margin, Churn Rate, and Sales & Marketing expenses—and synthesizes it into the LTV:CAC Ratio. This ratio tells you exactly how much value you are extracting from a customer compared to how much it cost to acquire them. A healthy ratio proves your business can scale profitably, while a poor ratio indicates that you are burning cash and need to rethink your product or marketing strategy immediately.
Understanding the LTV to CAC ratio requires breaking the math down into its foundational components. Here is how the calculator computes your business health:
LTV represents the total gross profit a single customer will bring to your business over the entirety of their relationship with you. The formula is:
LTV = (ARPU × Gross Margin) ÷ Customer Churn Rate
We multiply ARPU by Gross Margin because revenue is a vanity metric; you only get to keep the profit. We then divide by the churn rate, which mathematically estimates the average lifespan of a customer in months or years.
CAC is the total cost required to convince a potential customer to buy your product. The formula is:
CAC = Total Sales & Marketing Spend ÷ Number of New Customers Acquired
It is crucial to include all acquisition costs here, not just ad spend. You must include the salaries of your sales team, marketing software subscriptions, and agency fees.
Finally, we divide the LTV by the CAC. If your LTV is $3,000 and your CAC is $1,000, your LTV:CAC ratio is 3.0. This means for every $1 you spend on acquisition, you generate $3 in gross profit over the customer's lifetime.
StartupX is a B2B software company. Their ARPU is $200/month with an 80% gross margin, meaning they make $160 in profit per user per month. Their monthly churn rate is 5%. Using the formula ($160 ÷ 0.05), their LTV is $3,200. In a given month, they spend $10,000 on sales and marketing to acquire 10 new customers. Their CAC is $1,000. Dividing an LTV of $3,200 by a CAC of $1,000 yields a ratio of 3.2 to 1. This is widely considered the "Golden Ratio" in venture capital. The business is highly profitable and should pour more money into marketing to accelerate growth.
AppY is a consumer fitness app. Their ARPU is $15/month with a 90% margin ($13.50 profit). However, consumer apps suffer from high churn, sitting at 15% monthly. Their LTV is only $90 ($13.50 ÷ 0.15). They spend heavily on Meta Ads, resulting in a CAC of $60. Their LTV:CAC ratio is exactly 1.5 to 1. While they are technically making $30 more than they spend per customer, they are in the danger zone. After accounting for administrative costs, R&D, and server hosting, this business is likely losing money and needs to urgently lower its CAC or fix its churn problem.
A ratio of 3:1 is considered the industry standard for a healthy, scalable SaaS business. A ratio of 1:1 means you are losing money on every customer. A ratio of 5:1 or higher might actually mean you are under-investing in marketing and leaving market share on the table for your competitors to grab.
The Payback Period is the number of months it takes for a customer's gross profit to cover the cost of acquiring them (CAC). If your CAC is $500 and the customer generates $50 in profit per month, your payback period is 10 months. Most startups aim for a payback period of 12 months or less to ensure healthy cash flow.
Revenue is not cash in the bank. If a customer pays you $100 a month, but it costs you $30 a month in server fees and customer support to service them, your gross margin is 70%. If you calculate LTV based on the full $100 revenue, you will dangerously overestimate how much money you have available to spend on marketing.
You have three levers to pull: 1) Decrease CAC by optimizing ad campaigns and improving website conversion rates. 2) Increase ARPU by upselling features or raising prices. 3) Increase LTV by reducing churn, which is usually achieved by improving the core product experience and customer success operations.