CAC Calculator
Sales + marketing spend in a slice ÷ newly acquired customers counted the same window.
Open calculator →CAC Payback Period Calculator
Months to recover CAC using monthly gross profit per account (ARPU × margin unless you enter profit directly).
Overview
Use when finance asks how long until acquisition spend repays via gross profit. Expansion revenue can shorten reality but is not automatic in this base model.
When to use this calculator
- When you model gross profit per customer per month against CAC
- Before you cut or add spend while payback is creeping
- When expansion shortens real payback but you want the base case first
- When gross margin is thin and payback explodes even at steady ARPU
Rule of thumb
Long payback can be workable with cash in the bank; short payback can still hide weak expansion if you squint.
Terms used in this calculator
- CAC payback period
- Months of gross profit you need—per customer—to earn back acquisition spend.
- CAC
- Acquisition spend you assign divided by how many fresh paying customers you credit in that same window.
Calculator
CAC payback period
9.52 mo
Results are simplified estimates for educational purposes only and should not be treated as financial, accounting, legal, or tax advice. See our disclaimer for details.
Formula
CAC ÷ monthly gross profit per customer. Gross profit defaults to ARPU × gross margin % when direct field empty.
Example calculation
Using the default example values from the JSON seed for this tool:
- CAC
- 800
- ARPU (monthly revenue per customer)
- 120
- Gross margin
- 70
Result: 9.52 mo (CAC payback period)
How to interpret this result
Months to recover CAC from monthly gross profit per account when margin holds steady.
We compute gross profit as ARPU × gross margin % unless you enter gross profit directly.
Expansion ARR shortens effective payback but is not in this base view.
Common mistakes
- Using revenue instead of gross profit in the monthly contribution term.
- Assuming margin stays flat as you scale support-heavy accounts.
- Skipping sensitivity when ARPU or margin is uncertain.
What to do next
If payback slips, rerun CAC, gross margin inputs, or ARPA before approving more budget.
How to improve this result
- Improve monthly gross profit with packaging or COGS work before buying more ads.
- Trim CAC by fixing creative-offer fit on the coldest audiences first.
- Stress-test margin if new customers need heavy human onboarding.
Recommended tools
- Baremetrics SaaS metrics and subscription analytics dashboards.
- ChartMogul Subscription analytics for revenue, churn, and cohort reporting.
- ProfitWell Pricing and retention resources for subscription businesses.
FAQ
- Revenue instead of gross profit?
- Skews payback optimistic—margin belongs in denominator.
- Does annual prepay shorten payback visually?
- Cash hits early but monthly gross profit recognition may differ—watch accounting.
- High payback always bad?
- Long cycles can work with financing and expansion—context matters.
- Should CAC monthly match gross profit monthly?
- Yes—same customer cohort labeling.
- Pair with churn?
- Yes—thin margin plus high churn explodes perceived payback stability.
Related calculators
LTV:CAC Ratio Calculator
Estimated LTV ÷ estimated CAC using definitions you already aligned between teams.
Open calculator →MRR Calculator
Paying customers × average monthly recurring price after you convert plan mix into monthly amounts.
Open calculator →Affiliate disclosure
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