What is LTV/CAC?

LTV/CAC is one of the most critical metrics for determining whether growth is sustainable in SaaS and subscription-based businesses. It answers a single question with one ratio: "Is the money you spend to acquire a customer (CAC) lower than the value that customer brings you over their lifetime (LTV)?"

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What is LTV/CAC?

LTV/CAC refers to the ratio between the lifetime value (LTV – Lifetime Value) a customer provides to your company and the acquisition cost (CAC – Customer Acquisition Cost) you incur to win that customer.

Formula:

LTV/CAC = LTV ÷ CAC

This ratio is commonly used to measure:

• whether growth is healthy (unit economics),
• the sustainability of marketing and sales budgets,
• investability level

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What is LTV? (Lifetime Value)

LTV (Customer Lifetime Value) is the total contribution value a customer provides during their time with you. The most accurate approach is to calculate LTV on a gross profit basis.

How to calculate LTV in SaaS?

A simple approach for SaaS:

• ARPA (Average Revenue Per Account): average monthly revenue per account
• Gross Margin: (Revenue – direct costs) / Revenue
• Churn: monthly customer loss rate

LTV = (ARPA × Gross Margin) / Monthly Churn

Example:

• ARPA = $50/month
• Gross margin = 80%
• Monthly churn = 5% (0.05)

LTV = (50 × 0.80) / 0.05 = 40 / 0.05 = $800

Note: More detailed models also use net revenue retention and cohort-based lifespan approaches.

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What is CAC? (Customer Acquisition Cost)

CAC is the cost per customer acquired through your sales + marketing spending.

CAC = (Sales + Marketing Expenses) / Number of New Customers

Example:

• Monthly sales+marketing expense: $100,000
• New customers: 200
• CAC = 100,000 / 200 = $500

CAC typically includes:

• advertising spend
• sales team salaries/commissions
• marketing tools (CRM, email tool)
• agency fees
• events and sponsorships (if applicable)

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How to Calculate LTV/CAC? (Example)

Example:

• LTV = $800
• CAC = $250

LTV/CAC = 800 / 250 = 3.2

This value is generally considered "healthy" (though it varies by industry).

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What Should the Ideal LTV/CAC Ratio Be?

Although the "ideal" ratio varies by industry, margin, growth rate, and sales cycle, the common interpretation is:

• < 1 → unsustainable (loss per customer)
• 1 – 3 → marginal / room for improvement
• ≥ 3 → generally healthy (common target especially for SaaS)
• Very high (e.g. 6–10+) → may have opportunity to invest more in growth (checking channel scalability)

Important: Just because LTV/CAC is high doesn't mean "great." Sometimes a very high ratio indicates insufficient investment in marketing.

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Is LTV/CAC Enough Alone? Don't Forget Payback Period

Alongside LTV/CAC, you must also look at CAC Payback Period (CAC payback time).

Payback (months) = CAC / Monthly gross profit contribution

Example:

• CAC = $300
• Monthly gross profit contribution = $50
• Payback = 300 / 50 = 6 months

Interpretation:

• 3–9 months is generally acceptable for most SaaS (depends on segment and sales model)
• If too long (12–18+ months), cash flow risk increases and burn rate may become unsustainable

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Common Mistakes That Hurt LTV/CAC Ratio

1. Calculating LTV based on revenue and forgetting gross margin
2. Including only ads in CAC while leaving out sales costs
3. Measuring churn incorrectly (logo churn vs revenue churn)
4. Settling for "average" (not doing channel-based and cohort-based analysis)
5. Not reflecting the impact of discounts, refunds, and churn

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How to Improve LTV/CAC?

Reduce CAC

• improve targeting and offers
• optimize landing pages / funnels
• organic channels (SEO, referral)
• shorten sales cycle

Increase LTV

• strengthen onboarding (activation ↑)
• clarify product value (product-market fit)
• increase retention, reduce churn (customer success)
• upsell/cross-sell, plan upgrades

Increase Gross Margin

• cost optimization
• price revision
• packaging (tiers)

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Frequently Asked Questions

Is LTV/CAC used for every business model?

Most commonly used in subscription/SaaS and businesses with repeat purchases. Can also be calculated "per customer" in e-commerce.

LTV/CAC is high but growth is slow, why?

The channel might not be scaling, or marketing investment is too limited. Not "pushing harder" when the ratio is good sometimes slows growth.

How is LTV estimated in a new startup?

Early on, LTV estimates are uncertain because there's limited cohort data. This is why:

• short-term retention signals
• trial to paying conversion
• early churn trends

are used to validate the "direction."

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Conclusion: What is LTV/CAC?

LTV/CAC is the ratio of the value a customer brings you to the cost of acquiring that customer. For sustainable growth, LTV should be significantly higher than CAC; the common SaaS target is 3+ ratio. However, it's not enough on its own; it must always be evaluated together with CAC payback and churn/retention.