CAC payback by cohort
Catches channel/cohort decay before the blended number moves.
- Formula
- Cohort-level CAC / cohort monthly gross-margin revenue (curve over time)
- Unit
- months
- Models
- SaaS, Usage-based, Subscription, E-commerce
| All | Use blended CAC payback benchmarks (typically 6–18 months for B2B SaaS, shorter for B2C subscription) as a loose directional reference — cohort-level payback should rhyme with blended payback for stable channels; material divergence signals channel or cohort decay worth investigating.EST | Omega Point estimate |
What it is
CAC payback by cohort is the months required for a specific acquisition cohort to recover its customer acquisition cost through gross-margin-adjusted revenue. Unlike blended payback — which averages across all customers — cohort-level payback is calculated per acquisition period (e.g., customers acquired in Q3 2024) and tracked forward as a curve, showing how quickly that cohort cumulatively recovered its cost.
How to calculate it
For a given cohort: sum the total acquisition spend attributable to that cohort (the CAC). Then, for each subsequent month, accumulate that cohort's gross-margin revenue (revenue × gross margin %). Track the cumulative gross-margin total month by month until it crosses the initial CAC. The number of months to crossing is the cohort payback period. Plot multiple cohorts on the same chart to reveal whether recent cohorts are paying back faster or slower than earlier ones.
Why it matters
Cohort-level payback catches channel or product decay before the blended average moves. If your Q1 cohort paid back in 10 months but your Q4 cohort is tracking toward 18 months, you have a deteriorating channel or product problem — but the blended payback number may still look healthy because it includes the strong early cohorts. For any model with significant acquisition investment (SaaS, subscription, e-commerce, usage), this is the earlier-warning signal that the blended metric masks.
How to read it
There is no published benchmark for cohort-level CAC payback specifically. The cohort view is an analytical construction that organizations implement differently (some attribute CAC by channel, some by time period, some by segment), making cross-company comparison unreliable.
As an Omega Point directional reference: blended CAC payback benchmarks — which are reasonably well established — suggest healthy ranges of roughly 6–18 months for B2B SaaS and shorter for B2C subscription and e-commerce. Cohort-level payback for stable channels should roughly rhyme with the blended figure for the same period. If your most recent cohorts are tracking materially longer than earlier cohorts at the same time horizon, that divergence is the signal worth investigating, regardless of the absolute number. Use the blended-payback benchmark as a loose directional reference; the primary value of the cohort view is trend comparison within your own data, not external benchmarking.