What is a good LTV to CAC ratio?

The SaaS industry standard for a healthy LTV:CAC ratio is 3:1. This means you make 3 dollars for every 1 dollar spent acquiring a customer. A ratio of 1:1 means you are losing money (death spiral), and a ratio of 5:1 means you might be under-investing in marketing.

How do you calculate SaaS LTV?

Customer Lifetime Value (LTV) is calculated by multiplying the Average Revenue Per User (ARPU) by the Gross Margin percentage, and dividing the result by your Monthly Churn Rate.

Why do I need to include Gross Margin in LTV?

If you don't factor in Gross Margin (server costs, support, APIs), you are calculating revenue, not profit. Using Gross Margin ensures your LTV represents the actual cash you have available to recover your acquisition costs.

LTV vs CAC Calculator

Calculate your Customer Lifetime Value vs Acquisition Cost ratio to see if your SaaS is mathematically viable.

The Lifeblood of SaaS: Unit Economics

In the software world, revenue growth means nothing if your unit economics are broken. The LTV:CAC ratio (Customer Lifetime Value to Customer Acquisition Cost) is the ultimate litmus test for startup survival. It tells you exactly how much value you extract from a user compared to how much it cost you to get them.

The Rule of 3 (3:1 Ratio)

Venture capitalists and seasoned founders look for a benchmark ratio of 3:1. This means that for every $1 you spend on marketing, sales, and onboarding (CAC), you receive $3 back in pure profit over the customer’s lifespan (LTV).

Ratio < 1:1 (Death Spiral): You are losing money on every customer you acquire. Stop spending on Ads immediately and fix your product retention or pricing.
Ratio 1:1 – 2:1 (Danger Zone): You are surviving, but barely. One bad month of churn or an increase in ad costs will put you out of business.
Ratio 3:1 (Healthy Growth): You have achieved Product-Market Fit. Your business model is sustainable.
Ratio > 5:1 (Under-investing): You are highly profitable, but you are likely growing too slowly. You could afford to spend much more on marketing to capture market share.

Why Gross Margin Matters

A common mistake founders make is calculating LTV based strictly on Top-Line Revenue. If an AI user pays you $20/month, but it costs you $10/month in OpenAI API fees and server costs to support them, your Gross Margin is only 50%. Your true LTV must be calculated on the $10 profit, not the $20 revenue. Ignoring Gross Margin is the fastest way to run out of runway.

▶ 👨‍💻 Read the Financial Deep Dive (For Founders)

Financial Deep Dive: Modeling Customer Churn

The mathematical foundation of Customer Lifetime Value (LTV) relies heavily on the predictability of your Monthly Churn Rate. A high churn rate geometrically destroys your LTV, acting as a massive multiplier against your profitability.

The Inverse Churn Formula

Customer Lifetime (in months) is simply the inverse of your Monthly Churn Rate (1 / Churn). If your churn is 5%, your average customer stays for 20 months (1 / 0.05). If your churn spikes to 10%, the lifetime drops to just 10 months. This halving of the customer lifespan requires you to either double your pricing or cut your acquisition costs in half just to maintain the same ratio.

// The core unit economics formula
function calculateLTV(arpu, grossMargin, churnRate) {
    const marginDecimal = grossMargin / 100;
    const churnDecimal = churnRate / 100;
    
    // Profit per month = ARPU * Margin
    const monthlyProfit = arpu * marginDecimal;
    
    // Lifetime in months = 1 / Churn
    const lifetimeMonths = 1 / churnDecimal;
    
    return monthlyProfit * lifetimeMonths;
}

function calculateRatio(ltv, cac) {
    return (ltv / cac).toFixed(1);
}

When scaling paid acquisition, it is imperative that your CAC does not exceed your LTV payback period of 12 months. Any payback period exceeding 12 months requires significant venture capital to bridge the cash flow gap.

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