CAC Payback and LTV Modeling

Determines sustainable growth speed. CAC, LTV, payback.

Why CAC payback / LTV matter

These metrics determine sustainable growth speed. Strong unit economics support aggressive growth; broken unit economics limit reinvestment.

CAC calculation

• Total acquisition spend / new customers.
• Blended vs paid.
• Fully-loaded vs working-media-only.
• Channel-level variation.
• Source-level variation.
• Time-of-acquisition cost.

LTV calculation

• Cohort-based not average-based.
• Gross-profit LTV not revenue.
• Predicted vs observed.
• Segment variation.
• Source variation.
• Time-discounted future revenue.

Payback period

• Months to recover CAC from gross profit.
• SaaS sweet spot 12–18 months.
• DTC 3–6 months.
• Subscription DTC up to 12.
• Capital efficiency lens.

Advanced playbook

• Fully-loaded CAC.
• Gross-profit cohort-based LTV.
• Channel-level unit economics.
• Predicted LTV models.
• Payback period tracked monthly.
• Source-level LTV.
• Annual review with finance.
• Scenario modeling.
• Capital efficiency narrative.
• Investment gates on unit economics.

Mistakes

• Working-media CAC only.
• Average-based LTV.
• Revenue LTV not gross profit.
• Channel-level absent.
• Predicted LTV missing.
• Payback period ignored.
• Source-level not tracked.
• Annual review skipped.
• Scenario modeling absent.
• Investment gates missing.

Checklist

• Fully-loaded CAC
• Gross-profit cohort LTV
• Channel-level unit economics
• Predicted LTV models
• Payback period tracked
• Source-level LTV
• Annual review with finance
• Scenario modeling
• Capital efficiency narrative
• Investment gates

Part of the Marketing Finance series.