CAC payback period
How many months it takes for a new customer's contribution margin to earn back what you spent to acquire them. It's a cash question as much as a profit one: the longer the payback, the more money is tied up before growth pays for itself.
Read it off the cohort's cumulative CM1 curve, not from an average monthly margin. CM1, not CM2, because CM2 already deducts ad spend and would count CAC twice.
What is CAC payback?
When you acquire a customer, you pay the full cost up front and earn it back over time: first from their first order's margin, then from every reorder. Payback is the month when the running total finally covers the acquisition cost.
LTV:CAC tells you whether a customer is worth acquiring. Payback tells you how long you'll be out of pocket. Two cohorts can have the same LTV:CAC at 12 months, but if one pays back in month 1 and the other in month 9, they need very different amounts of cash to scale.
How it's calculated
Build the cohort's cumulative CM1 per customer month by month, then find the first month it reaches new customer CAC.
| Input | Source and range | What it gives us |
|---|---|---|
| ncac | Acquisition spend รท first-time customers, the cohort's month | The amount to recover |
| cm1_by_month | Cohort CM1 from delivered orders, by month since first order | What each month earns back |
| cohort_size | First-time customers in the cohort | Turns totals into per-customer values |
How to track it over time
Payback is a property of a cohort, so track it cohort by cohort. A new cohort can't show a 6-month payback until it's 6 months old, but you can see early whether it's ahead of or behind older cohorts.
- 1Fix nCAC per cohortUse the CAC from the cohort's own acquisition month.
- 2Add CM1 monthlyEach month, add the cohort's delivered-order CM1 to its running total.
- 3Track % recoveredCompare cohorts on % of CAC recovered at the same age.
- 4Mark the crossingThe first month at 100% or more is that cohort's payback period.
Worked examples
Example 1: A cohort that pays back in month 3
An illustrative January cohort acquired at a new customer CAC of โน570. Average first order โน1,200 at a 38% CM1 margin.
| Month since first order | Cumulative CM1 per customer | % of โน570 CAC recovered |
|---|---|---|
| 0 (first order) | โน456 | 80% |
| 1 | โน502 | 88% |
| 2 | โน551 | 97% |
| 3 | โน593 | 104% ยท paid back |
| 4 | โน631 | 111% |
| 5 | โน669 | 117% |
| 6 | โน707 | 124% |
- Day 1The first order returns โน456, 80% of CAC. Only โน114 is left to recover.
- Month 3Reorders close the gap. From here on, every rupee of CM1 is profit before operational costs.
- Flat formulaโน707 over 6 months is โน118 a month, which suggests 4.8 months. It misses how front-loaded the margin is.
Example 2: Same brand, deeper discount, slower payback
A later illustrative cohort acquired with a heavy first-order discount and a higher CAC of โน720.
Using payback to decide
The right payback target depends on how much cash you have and how fast customers reorder. These are starting points for a replenishable D2C product.
Common mistakes
- Using revenue instead of CM1Revenue pays back CAC on paper months before margin actually does.
- Flat monthly averagesIgnore that the first order does most of the work. Read the cumulative curve.
- Blended CACMakes payback look faster by spreading spend over repeat buyers.
- Counting placed COD ordersRTO orders return no margin. Recover CAC only from delivered orders.
Frequently asked questions
What is a good CAC payback period?
Whatever your cash can carry. A bootstrapped brand may need payback on the first order. A funded brand can afford months, as long as later cohorts aren't slipping.
Is payback on the first order realistic?
For high-AOV, high-margin products, yes. It means first-order CM1 per customer is at least nCAC, so every reorder is upside.
How is payback different from LTV:CAC?
LTV:CAC says how much comes back by the end of a window. Payback says when it reaches 1.0. You need both: one is about profit, the other about cash.
Related metrics
Know when growth starts paying for itself
BooleanMaths tracks cumulative CM1 per customer for every acquisition cohort against its new customer CAC, so you can see payback by month, channel and campaign.
CAC payback period
How many months it takes for a new customer's contribution margin to earn back what you spent to acquire them. It's a cash question as much as a profit one: the longer the payback, the more money is tied up before growth pays for itself.
Read it off the cohort's cumulative CM1 curve, not from an average monthly margin. CM1, not CM2, because CM2 already deducts ad spend and would count CAC twice.
What is CAC payback?
When you acquire a customer, you pay the full cost up front and earn it back over time: first from their first order's margin, then from every reorder. Payback is the month when the running total finally covers the acquisition cost.
LTV:CAC tells you whether a customer is worth acquiring. Payback tells you how long you'll be out of pocket. Two cohorts can have the same LTV:CAC at 12 months, but if one pays back in month 1 and the other in month 9, they need very different amounts of cash to scale.
How it's calculated
Build the cohort's cumulative CM1 per customer month by month, then find the first month it reaches new customer CAC.
| Input | Source and range | What it gives us |
|---|---|---|
| ncac | Acquisition spend รท first-time customers, the cohort's month | The amount to recover |
| cm1_by_month | Cohort CM1 from delivered orders, by month since first order | What each month earns back |
| cohort_size | First-time customers in the cohort | Turns totals into per-customer values |
How to track it over time
Payback is a property of a cohort, so track it cohort by cohort. A new cohort can't show a 6-month payback until it's 6 months old, but you can see early whether it's ahead of or behind older cohorts.
- 1Fix nCAC per cohortUse the CAC from the cohort's own acquisition month.
- 2Add CM1 monthlyEach month, add the cohort's delivered-order CM1 to its running total.
- 3Track % recoveredCompare cohorts on % of CAC recovered at the same age.
- 4Mark the crossingThe first month at 100% or more is that cohort's payback period.
Worked examples
Example 1: A cohort that pays back in month 3
An illustrative January cohort acquired at a new customer CAC of โน570. Average first order โน1,200 at a 38% CM1 margin.
| Month since first order | Cumulative CM1 per customer | % of โน570 CAC recovered |
|---|---|---|
| 0 (first order) | โน456 | 80% |
| 1 | โน502 | 88% |
| 2 | โน551 | 97% |
| 3 | โน593 | 104% ยท paid back |
| 4 | โน631 | 111% |
| 5 | โน669 | 117% |
| 6 | โน707 | 124% |
- Day 1The first order returns โน456, 80% of CAC. Only โน114 is left to recover.
- Month 3Reorders close the gap. From here on, every rupee of CM1 is profit before operational costs.
- Flat formulaโน707 over 6 months is โน118 a month, which suggests 4.8 months. It misses how front-loaded the margin is.
Example 2: Same brand, deeper discount, slower payback
A later illustrative cohort acquired with a heavy first-order discount and a higher CAC of โน720.
Using payback to decide
The right payback target depends on how much cash you have and how fast customers reorder. These are starting points for a replenishable D2C product.
Common mistakes
- Using revenue instead of CM1Revenue pays back CAC on paper months before margin actually does.
- Flat monthly averagesIgnore that the first order does most of the work. Read the cumulative curve.
- Blended CACMakes payback look faster by spreading spend over repeat buyers.
- Counting placed COD ordersRTO orders return no margin. Recover CAC only from delivered orders.
Frequently asked questions
What is a good CAC payback period?
Whatever your cash can carry. A bootstrapped brand may need payback on the first order. A funded brand can afford months, as long as later cohorts aren't slipping.
Is payback on the first order realistic?
For high-AOV, high-margin products, yes. It means first-order CM1 per customer is at least nCAC, so every reorder is upside.
How is payback different from LTV:CAC?
LTV:CAC says how much comes back by the end of a window. Payback says when it reaches 1.0. You need both: one is about profit, the other about cash.
Related metrics
Know when growth starts paying for itself
BooleanMaths tracks cumulative CM1 per customer for every acquisition cohort against its new customer CAC, so you can see payback by month, channel and campaign.