CAC Payback Period Calculator

How to calculate CAC payback period

CAC payback period is the number of months of gross profit it takes to earn back the cost of acquiring a customer. Four steps:

1. Calculate CAC. Total sales and marketing spend for a period divided by the new customers won in that period.
2. Find the monthly ARPA of new customers. Use what newly acquired customers pay, not the average across your whole base, because new customers are often on different plans and prices.
3. Multiply ARPA by gross margin to get monthly gross profit per customer.
4. Divide CAC by monthly gross profit. The result is payback in months.

Board decks often run the same calculation on totals: sales and marketing spend divided by new MRR multiplied by gross margin. The Benchmarkit 2025 report uses the annual version, sales and marketing expenses / (new customer ARR x gross margin) x 12.

Worked example

A mid-market SaaS company spends $2,400 to acquire each customer. New customers pay $200 a month, gross margin is 80%, and 2% of customers cancel each month.

• Monthly gross profit per customer: $200 x 0.80 = $160
• CAC payback: $2,400 / $160 = 15 months
• Payback on revenue: $2,400 / $200 = 12 months
• Churn-adjusted payback: ln(1 - 2,400 x 0.02 / 160) / ln(0.98) = 17.7 months
• Customers still active at month 15: 0.98^15 = 74%

Fifteen months is inside Bessemer's 18-month target for mid-market companies, but it would miss the 12-month SMB target. And because about a quarter of the cohort has cancelled by month 15, the cohort as a whole needs closer to 18 months to earn its acquisition cost back.

Monthly vs annual billing: cash and economic payback

The formula measures economic payback, in months of gross profit. Billing terms change cash payback instead. A customer who prepays a $2,400 annual plan hands you the whole first year on day one, which helps runway but does not make the customer more profitable. Keep the two apart: cash payback for runway planning, economic payback for judging acquisition efficiency.

If you work from annual figures, keep the units straight. ARR-based payback (CAC / (ACV x gross margin)) comes out in years, so multiply by 12 to compare it with monthly benchmarks.

Common CAC payback mistakes

• Using revenue instead of gross profit. At an 80% gross margin, revenue payback looks 20% shorter than the real thing.
• Using the ARPA of your whole customer base. Older customers may have expanded or be on legacy prices. Use what new customers pay.
• Relying on blended CAC. Organic signups make paid channels look cheaper. Check payback per channel before scaling one.
• Ignoring early churn. Customers who cancel in the first months never pay back their share. Add your churn rate to see the cohort view.
• Not lagging spend. With a long sales cycle, this quarter's spend wins next quarter's customers. Compare new customers with the spend that produced them.

What's a good CAC payback period?

Bessemer Venture Partners sets its targets by segment because contract values and churn differ so much between SMB and enterprise customers. It also reports an average payback of 15 months for its companies at $1–10M ARR, rising as companies scale. Aleph's analysis of Benchmarkit data for full-year 2025 (198 companies reporting payback) found the median improved from 18 months in 2024 to 16 months.

David Skok's older and stricter rule in his SaaS Metrics guide is that startups should recover CAC in less than 12 months. The Benchmarkit 2025 report sums up the current view: about 12 months is the common wisdom, but payback is highly correlated with contract value.

How this calculator works

• Segment sets the target used in the verdict: 12 months for SMB, 18 for mid-market and 24 for enterprise.
• CAC payback is CAC / (monthly ARPA x gross margin). Payback on revenue is CAC / monthly ARPA, shown for comparison.
• Churn-adjusted payback treats your customers as a cohort in which the churn rate you enter cancels every month. It finds the month n where the cohort's cumulative gross profit equals CAC: CAC = monthly gross profit x (1 - (1 - churn)^n) / churn. If gross profit / churn (gross margin LTV) is below CAC, the cohort never pays back.
• The verdict is green within your segment's target, orange above the target up to 24 months, and red beyond 24 months.
• Limitations: ARPA, gross margin and churn are held constant, so expansion revenue, price changes and early-life churn spikes are not modeled. Cash timing from annual prepayments is ignored. The math runs in your browser.

How to shorten CAC payback

• Raise ARPA with pricing, packaging and higher-value customers.
• Lower CAC by moving spend to the channels that bring in retained customers most cheaply.
• Improve gross margin by cutting hosting, support and payment costs per customer.
• Reduce early churn with better onboarding, so more of each cohort survives to payback.
• Shorten the sales cycle and improve trial-to-paid conversion.

Related metrics and guides

• CAC payback period, the full guide including cohort payback
• CAC, what to include in acquisition cost
• LTV:CAC ratio, profitability over the full customer lifetime
• Magic number and burn multiple, efficiency at company level

Check lifetime profitability with the LTV:CAC ratio calculator, or get your gross margin LTV from the LTV calculator.