Customer lifetime value (LTV) is the total value a customer brings over the entire relationship with a business, not just the first order.
Ad platforms mostly optimize and report on the first conversion. For brands whose economics depend on repeat purchases or renewals, that means the reports systematically undervalue some campaigns and overvalue others. First-order ROAS is covered in What Is ROAS?.
Calculating LTV
Repeat-purchase e-commerce
| Component | Example |
|---|---|
| Average order value | $60 |
| Orders per year | 4 |
| Average customer lifespan | 2 years |
| Gross margin | 45% |
Revenue over the relationship is 480. Margin-based LTV is 216.
Ad spend is paid out of margin, not revenue. That makes margin-based LTV the right number to compare with acquisition cost. Comparing CAC with revenue LTV overstates how much a customer is worth buying.
Subscription businesses
For subscriptions, LTV comes from monthly churn:
LTV = monthly revenue per user × gross margin ÷ monthly churn rate
A SaaS product at 40 × 0.80 ÷ 0.05 = 1,280, which shows why retention work can move acquisition budgets as much as ad optimization does.
LTV, CAC, and Payback
Customer acquisition cost (CAC) is total marketing and sales spend divided by new customers acquired.
LTV to CAC ratio
A ratio around 3:1 is widely cited as healthy. It is a rule of thumb, not a hard threshold. Near 1:1, each customer barely pays for themselves. Far above 3:1 often means the business is underinvesting in growth.
Payback period
Payback adds the cash dimension. In the subscription example, each customer generates 200, payback takes 32 = 6.25 months, while the LTV-to-CAC ratio is a comfortable 3.2. A venture-backed company can carry that gap. A bootstrapped one may not be able to fund six months of float for every new customer.
The First-Order ROAS Trap
Consider two Meta campaigns for a skincare brand:
| Campaign A: 30% off first order | Campaign B: full price | |
|---|---|---|
| First-order ROAS | 2.8 | 1.6 |
| Customers still buying after 6 months | 18% | 42% |
| 6-month revenue per customer | $74 | $139 |
On first-order ROAS, A looks nearly twice as good. On six-month cohort value, B wins clearly, because discount-driven buyers often don’t return. The platforms’ default reporting never shows this. The numbers above are illustrative, but the pattern is common in consumer subscription and replenishment categories.
Tracking LTV in GA4
GA4’s Explorations include a cohort exploration, which shows how users acquired in the same period behave in the following weeks, and a user lifetime exploration, which compares total revenue by first user source or campaign. Together they turn “which campaign had better ROAS” into “which campaign brought better customers.”
GA4 also offers predictive metrics, including predicted revenue over the next 28 days. According to Google, they require at least 1,000 returning users who triggered the relevant condition and 1,000 who didn’t within a seven-day period in the last 28 days, plus purchase events with value and currency. Many smaller properties never qualify.
Bringing LTV Into Bidding
LTV information flows into ad systems three ways:
- Lower first-order ROAS targets where repeat rates are proven, letting later orders complete the margin.
- New customer acquisition goals in Google Ads, which let bidding value new customers more than returning ones.
- Value-based bidding with predicted LTV, where the conversion value sent to Google or Meta reflects expected lifetime value by segment instead of basket size. This needs a solid first-party data pipeline, as covered in What Is a First-Party Data Strategy?.
Common Mistakes
- Comparing CAC with revenue-based LTV instead of margin-based LTV.
- Using one blended LTV for every channel, when customers from different sources behave very differently.
- Assuming long customer lifespans for a young business without the history to support them.
Summary
LTV measures what a customer is worth across the relationship and should be calculated on margin. The LTV-to-CAC ratio shows profitability, and payback period shows cash strain. First-order ROAS hides repeat behavior, so cohort analysis often reverses which campaigns deserve more budget. Feeding LTV into targets and conversion values aligns ad platforms with long-term profit.