# CAC payback period

> CAC payback is the number of months a company needs to earn back what it spent to acquire a customer, from that customer's gross margin. A common formula is customer acquisition cost divided by monthly recurring revenue per new customer times gross margin. A shorter CAC payback means growth needs less cash. Compare it by segment, because enterprise and self-serve customers pay back differently.

Source: https://delsivo.com/glossary/cac-payback · Updated 2026-11-06

## Key takeaways

- Payback months = CAC divided by (new MRR per customer times gross margin).
- Use gross margin, not revenue, or payback looks shorter than it is.
- Fully loaded CAC includes sales and marketing salaries, not only ad spend.

## How to calculate CAC payback

First find CAC: total sales and marketing cost in a period divided by new customers won in it. Then divide CAC by the monthly gross profit each new customer brings.

Example: a company spends $300,000 on sales and marketing in a quarter and wins 50 customers, so CAC is $6,000. Each pays $500 a month at an 80 percent gross margin, which is $400 of gross profit a month. CAC payback is 6,000 divided by 400: 15 months.

## What CAC payback tells a fund

Payback shows how long each new customer ties up cash. Combined with churn, it shows whether customers stay long enough to pay back at all. A company with 15-month payback and customers who leave after a year is losing money on every sale, however fast it grows.

## Mistakes to check for

- Paid-only CAC that leaves out salaries, tools and agency fees.
- Revenue used instead of gross margin.
- Blended CAC that mixes free word-of-mouth customers with expensive outbound ones.
- Costs and customers from different periods, when sales cycles are long.

## Common confusions

- CAC payback versus LTV to CAC: payback is a time; LTV to CAC is a ratio of lifetime value to cost.
- CAC payback versus [burn multiple](https://delsivo.com/glossary/burn-multiple): payback covers acquisition only; burn multiple covers all spending.
- A short payback in one channel may not hold when that channel is scaled.

## Frequently asked questions

### What is a good CAC payback period?

It depends on the segment, contract length and churn. Customers must stay well beyond the payback period, so compare it with retention rather than a single target.

### Should CAC payback use revenue or gross margin?

Gross margin. Revenue ignores the cost of serving the customer and makes payback look shorter than it is.

### How do early-stage startups measure CAC?

Often roughly, with few customers. State the period, the costs included and the number of customers, and treat the figure as an early signal.

## Related pages

- [Burn multiple](https://delsivo.com/glossary/burn-multiple)
- [Net revenue retention](https://delsivo.com/glossary/net-revenue-retention)
- [MRR](https://delsivo.com/glossary/mrr)
- [Claims and evidence](https://delsivo.com/claims-and-evidence)