LTV:CAC Ratio — Calculation, Benchmarks, and Pitfalls

Why LTV:CAC Is the Most Important Marketing Ratio

LTV:CAC (Customer Lifetime Value to Customer Acquisition Cost) is the single metric that best captures whether your business model is sustainable. Too low and you're building a company that loses money on every customer. Targets that are too aggressive lead to under-investment and slow growth. Understanding the ratio — and calculating it correctly — is fundamental to growth strategy.

Our marketing analytics team includes LTV:CAC in every marketing measurement framework we build.

Calculating LTV

LTV (Lifetime Value) represents the total revenue or gross profit a customer generates over their entire relationship with your business.

Simple LTV (for early-stage or limited data)

LTV = Average Order Value × Average Purchase Frequency × Average Customer Lifespan

Example: £80 AOV × 4 purchases/year × 2.5 years = £800 LTV

Gross Profit LTV (More Accurate)

LTV = (Average Order Value × Gross Margin %) × Purchase Frequency × Lifespan

Example: £80 × 55% margin × 4 × 2.5 = £440 gross profit LTV

Use gross profit LTV when comparing to CAC — this represents what the customer actually returns to the business, not the revenue that gets partially consumed by COGS.

Predicted LTV (ML-Based)

For businesses with sufficient transaction history (12+ months, 1,000+ customers), predictive LTV models trained on early customer behavior can project lifetime value at the point of acquisition. This is the most actionable but most complex to implement.

The LTV:CAC Ratio

LTV:CAC = LTV / CAC

Benchmarks (B2C and SaaS, gross profit LTV vs. fully-loaded CAC):

Payback Period: The Missing Dimension

LTV:CAC tells you whether customers will be profitable eventually. Payback period tells you when. A 5:1 LTV:CAC ratio with a 48-month payback requires significant capital to finance the gap. A 3:1 ratio with a 6-month payback is far more capital-efficient.

Payback Period = CAC / (Monthly Revenue per Customer × Gross Margin %)

Sustainable businesses target payback periods of 6–18 months. Venture-backed growth-mode businesses can tolerate 24–36 months.

Common LTV:CAC Pitfalls

• Revenue LTV vs. Gross Profit LTV: Using revenue LTV against fully-loaded CAC overstates the ratio. Use gross profit LTV consistently.
• Average LTV across all channels vs. channel-specific LTV: Customers acquired via organic often have higher LTV than paid customers. Averaging them hides this.
• Optimistic lifespan assumptions: Using theoretical maximum lifespan rather than observed churn rates produces LTV figures that will never materialize.
• Ignoring CAC overhead: Using ad spend only for CAC understates acquisition cost and overstates the ratio.

Build LTV and CAC calculation in BigQuery joining transaction data, customer data, and marketing spend. Our analytics team builds these models. Contact us for help implementing LTV:CAC tracking.