LTV:CAC Calculator

Estimate customer lifetime value, acquisition payback, and LTV:CAC ratio from monthly ARPA, gross margin, churn or retention, and CAC.

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Inputs

Retention assumption

Status

Needs improvement

1.60x

Customers are profitable, but acquisition efficiency is below the typical 3x target.

Customer lifetime

20 mo

Calculated as 1 ÷ monthly churn. Zero churn is shown as not meaningful, not infinity.

Customer LTV

$1,600

Monthly ARPA × gross margin × estimated lifetime.

LTV:CAC ratio

1.60x

Gross profit LTV divided by CAC. SaaS teams often target 3x or higher.

CAC payback

12.5 mo

CAC ÷ monthly gross profit, plus optional sales cycle delay.

Monthly assumptions

Monthly gross profit per customer: $80

Implied monthly churn: 5%

Implied monthly retention: 95%

Approx. annual revenue per account: $1,200

LTV:CAC formula and interpretation

LTV:CAC compares the gross profit you expect from a customer against what it costs to acquire them. This calculator uses monthly inputs, so churn, retention, lifetime, and payback are all expressed in months.

Customer lifetime

1 ÷ monthly churn rate

Gross profit LTV

Monthly ARPA × gross margin × customer lifetime

LTV:CAC

Gross profit LTV ÷ CAC

CAC payback

CAC ÷ monthly gross profit + optional sales cycle delay

How to read the result

Under 1x: Acquisition is value destructive unless there is a strong strategic reason.

1x to 3x: Customers are profitable, but the motion likely needs better retention, pricing, margin, or CAC.

3x to 5x: Generally healthy for SaaS and subscription businesses.

5x+: Very efficient. You may be under-investing in acquisition if growth is constrained.

Need a fuller SaaS model?

LTV:CAC is a quick read on unit economics. For board decks and fundraising, model cohorts, expansion revenue, churn, sales capacity, and cash burn together.

Keep modeling

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Use these next-step tools and Excel templates to turn the quick calculation into a more complete finance workflow.