averagecac.com

The single most-cited SaaS efficiency metric

CAC Payback Period

How many months of gross profit per customer it takes to recoup their acquisition cost. Payback period is the canonical answer to the question “is this customer economically worth acquiring?” with one number instead of the four you need for LTV:CAC.

The formula

Payback Period (months) = CAC ÷ (Monthly ARPU × Gross Margin)

The denominator is monthly gross profit per customer. Multiply ARPU by gross margin to get gross profit per dollar of revenue, then divide CAC by that monthly figure. Result is the number of months before the customer's gross profit covers what you spent to acquire them.

What “good” looks like

The tiers below are reference bands operators commonly use, calibrated against the numbers our cited primary sources publish. The Optifai n=939 B2B SaaS dataset reports a 15-month median overall, with ACV-segmented ranges of 8-12 months (SMB), 14-18 (mid-market), and 18-24 (enterprise) - see Optifai 2026 for the raw bands.

TierMonthsNotes
ExceptionalUnder 12SMB SaaS with product-led growth, viral mechanics, or high transactional revenue. Within Optifai's SMB band lower bound.
Strong12-18Around the Optifai overall B2B median (15 months) and within the mid-market band.
Median range14-24Spans Optifai's mid-market (14-18) and enterprise (18-24) bands. Most B2B SaaS lands here.
Weak24-36Above the upper bound of Optifai's enterprise band. Tolerable for high-NRR companies; weak otherwise.
DistressedOver 36A 3+ year payback only works with extraordinary retention. Most companies in this band are over-spending on growth.

Why payback often wins over LTV:CAC

LTV depends on three forward-looking inputs (gross margin, ARPU, churn), all of which have to be assumed. Payback depends on two backward-looking inputs (CAC, current gross profit per customer), both of which are observable from current financials. When you report payback, you're not asking anyone to trust your churn assumption.

For a more complete view that combines both, see our LTV:CAC ratio page.

Common questions

Common payback questions

What is a good CAC payback period?
Optifai's 2026 B2B SaaS dataset (n=939) reports an overall median of 15 months with SMB at 8-12, mid-market at 14-18, and enterprise at 18-24. Under 12 months is exceptional within the SMB band; the strong/healthy range is 12-18 months. Anything above 24-36 months is weak unless retention is extraordinary, and over 36 months typically signals over-spending. See our benchmarks pages for industry-specific cuts from First Page Sage 2024.
How do I compute CAC payback?
CAC payback (months) = CAC / (Monthly ARPU × Gross Margin). The denominator is monthly gross profit per customer. CAC is the numerator from your full S&M spend divided by net-new customers. ARPU is average revenue per customer per month (annual ARPU / 12). Gross margin is your gross profit as a percentage of revenue.
Why is payback more useful than LTV:CAC?
LTV requires a churn assumption that compounds over the projected lifetime, so small assumption errors produce large output errors. Payback depends only on current CAC and current gross profit per customer, both observable from this quarter's financials. For external reporting, payback is more defensible. For internal modelling, LTV:CAC is fine if your churn assumption is grounded.
Does payback period account for churn?
Not directly. Payback is computed against current gross profit per customer, assuming the customer is still around to pay you. If you have meaningful early-customer churn, your effective payback is longer than the formula suggests. Some operators discount payback by expected churn within the payback window, but that's a refinement.