CAC payback formula in Excel or Google Sheets
Put the inputs in column B from row 2, then paste the formulas below. They work the same in Excel and Google Sheets.
| Cell | What | Value or formula | Example |
|---|---|---|---|
| B2 | Customer acquisition cost ($) | 1800 | 1800 |
| B3 | Monthly revenue per customer ($) | 150 | 150 |
| B4 | Gross margin (%) | 80 | 80 |
| B6 | Monthly gross profit per customer ($) | =ROUND(B3*B4/100,2) | 120 |
| B7 | CAC payback (months) | =ROUND(B2/B6,1) | 15 |
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Frequently asked questions
- How do you calculate CAC payback?
- Divide the acquisition cost by the gross profit one customer brings each month. $1,800 CAC with $150 monthly revenue at 80% margin gives $120 of monthly profit, so payback takes 15 months.
- What is a good CAC payback period?
- Many SaaS companies aim for 12 months or less; 12 to 18 months is common in mid-market; beyond 24 months growth becomes expensive to fund. Compare it with how long customers actually stay.
- Why use gross margin instead of revenue?
- Revenue overstates what is left to repay acquisition: hosting, support and payment fees come out first. Using gross margin gives the real time to break even.
About the author
Abdessamad Ghanem
Customer Experience & Customer Success Consultant · Founder of Clarivoxx
Abdessamad Ghanem works across Customer Support, Sales, Customer Success, Account Management and Partner Management. He writes Clarivoxx Insights for B2B SaaS professionals who own retention, adoption and customer outcomes.