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LTV guide: formula, customer lifetime, cohort models, and LTV:CAC

A practical LTV guide covering shortcut formulas, gross profit vs revenue LTV, customer lifetime, cohort-based models, and how to connect LTV to CAC and payback.

Written by MetricKit EditorialReviewed by MetricKit Editorial ReviewUpdated 2026-05-25
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Best for

Founders, growth leaders, finance partners, and operators trying to decide what a customer is really worth before they set spend targets or growth expectations.

Decision

Whether the current LTV estimate is trustworthy enough to use in CAC targets, payback planning, and broader unit-economics decisions.

Use it when

You need one parent page before you branch into churn sensitivity, customer lifetime, cohort modeling, or LTV:CAC interpretation.

Reviewed by

MetricKit editorial review for SaaS unit economics planning.

Reviewed to keep LTV, churn, customer lifetime, and gross-margin assumptions aligned across the SaaS metrics cluster.
Topic hub

Understand LTV with more confidence

Start here for the main LTV question, then go deeper into customer lifetime, churn and margin sensitivity, cohort-based modeling, and the bridge into LTV:CAC.

Related guides
Core definitions
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LTV Calculator
SaaS example (ARPA $200; margin 80%; churn 3%)
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Quick answer

LTV (Lifetime Value) is the value you expect to earn from a customer over time. For operating decisions, the number is usually most useful when it is based on gross profit, not just revenue. The real question is not only how to calculate LTV, but how much confidence you should have in that estimate before you use it to justify CAC, payback, or growth plans.

A common shortcut

LTV ~= (ARPA * gross margin) / churn rate (with consistent time units).

When the shortcut is good enough

  • The business has relatively stable churn and limited expansion noise.
  • You need a quick planning estimate before you build a heavier cohort model.
  • ARPA, gross margin, and churn all come from the same segment and the same time unit.

When the shortcut breaks

  • Expansion revenue is significant and simple churn formulas understate value timing.
  • Churn changes over time, especially when early churn is much higher than later churn.
  • Different segments behave differently and blended averages hide what is really happening.

The assumptions that matter most

  • Use gross margin, not operating margin, when the number is meant to support CAC and payback decisions.
  • Match monthly ARPA with monthly churn, or annual ARPA with annual churn.
  • Be explicit about logo churn vs revenue churn because the two can tell very different stories.

Customer lifetime is often the next question

  • If you want to understand how long customers actually survive, go next to Customer lifetime.
  • If you need to see how fragile the estimate is, go next to LTV sensitivity.
  • If the shortcut feels too thin, go next to Cohort LTV forecasting.

What to pair with LTV

  • Use CAC and payback when the question is whether acquisition still works in cash terms.
  • Use LTV:CAC when the question is long-term sustainability, but only after you align definitions.
  • Use NRR/GRR and cohort retention when expansion or contraction changes the lifetime story.

Common mistakes

  • Using revenue LTV while comparing it to fully-loaded CAC.
  • Mixing monthly churn with annual ARPA or other unit mismatches.
  • Letting one low blended churn number hide segment instability.
  • Treating a shortcut estimate as precise when the business clearly needs cohorts.

FAQ

Is LTV the same as revenue per customer-
Not necessarily. LTV is ideally based on gross profit over time, not just revenue, and depends on retention/churn.
What churn should I use-
Use customer churn for a simple model, but consider revenue churn (NRR/GRR) if expansion and downgrades matter for your business.
When should I stop using the simple LTV formula-
Move beyond the shortcut when churn changes materially by tenure, expansion matters, or segment behavior differs enough that one blended estimate is misleading. That is the point where cohort-based LTV becomes more trustworthy.

More in saas metrics

Unit economics hub: CAC, LTV, payback, and runway (a practical stack)
A practical hub for unit economics: CAC, fully-loaded CAC, LTV, payback, margin impacts, burn multiple, and runway planning.
Unit economics guide: ARR, CAC, LTV, payback, and growth efficiency
A practical unit economics guide to how ARR, CAC, LTV, payback, and LTV:CAC work together when you judge growth quality, cash efficiency, and scale readiness.
LTV sensitivity: how churn and margin change LTV
A practical guide to LTV sensitivity: vary churn and gross margin to see how gross profit LTV changes under realistic scenarios.
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LTV sensitivity: how churn and margin change LTV →