# CAC Payback Period

> The number of months it takes a new customer to repay what you spent acquiring them.

- This is the markdown version of: https://www.productgrowth.blog/p/cac-payback-period (cite that URL)
- Type: Glossary term — Months to earn back acquisition cost
- Tags: Metrics
- ~560 words

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CAC payback period is the number of months it takes a new customer's gross profit to repay what you spent acquiring them. Every customer starts out as money you're owed: you paid the [acquisition cost](https://www.productgrowth.blog/p/customer-acquisition-cost-cac) up front, and they pay you back in monthly installments. Until they do, your growth eats cash.

## How to calculate CAC payback period

> **Formula:** CAC payback (months) = CAC ÷ (monthly revenue per customer × gross margin). At company level: sales and marketing spend in a period ÷ (new MRR added that period × gross margin).

The gross margin term is where most of the internet gets this wrong. Half the calculators ranking for this metric divide CAC by raw MRR. But **customers repay you in gross profit, not revenue**, so the revenue version always flatters you. Same goes for the numerator: use [fully loaded sales and marketing cost](https://www.thesaascfo.com/cac-payback-period/?utm_source=productgrowth.blog), salaries and tools included, not just ad spend.

Worked example: you spend $1,200 to land a customer paying $100 a month at 80% gross margin. Revenue math says 12 months. Margin math says $1,200 ÷ $80 = 15 months. That one skipped term just hid three extra months of being underwater. Run both and trust the uglier number.

## What is a good CAC payback period?

Under 12 months is the standard answer for SaaS, and it works as a first filter. The honest answer depends on who you sell to. ICONIQ's top-quartile data, compiled in [Airtree's benchmark guide](https://www.airtree.vc/open-source-vc/startup-metrics-cac-payback-and-ltv-cac-ratio?utm_source=productgrowth.blog), shows how high the bar sits for the best companies, while the by-segment rules of thumb are looser:

| Segment | Healthy CAC payback |
| --- | --- |
| Early stage, top quartile (ICONIQ) | ~3 months |
| Growth stage, top quartile (ICONIQ) | ~7 months |
| SMB sales, rule of thumb | Under 12 months |
| Mid-market, rule of thumb | Under 18 months |
| Enterprise, rule of thumb | Under 24 months |

Retention bends these numbers. [Growth Unhinged's survey of 660 private SaaS companies](https://www.growthunhinged.com/p/your-guide-to-cac-payback-period?utm_source=productgrowth.blog) pairs payback with net dollar retention: below 100% NDR you want payback under 12 months, because [churn](https://www.productgrowth.blog/p/churn-rate) keeps clawing the repayment back. At 150%+ NDR, a 20-month payback can still work, since expansion revenue keeps paying you long after the initial sale.

One thing the textbook definition hides: **payback is a cash metric, not a profitability metric**. A customer on annual prepay repays your cash on day one even when the formula reads 15 months. And it says nothing about what happens after repayment. A customer who churns in month 10 of a 15-month payback never paid you back at all. That's why payback sits alongside [lifetime value](https://www.productgrowth.blog/p/customer-lifetime-value-ltv), never in place of it.

#### What is a good CAC payback period for SaaS?

Under 12 months is the common bar for SaaS. Top-quartile early-stage startups recover CAC in about 3 months, while enterprise-focused companies can run up to 24 months because contracts are bigger and retention is stronger.

#### Do you include gross margin in the CAC payback formula?

Yes. Divide CAC by monthly revenue per customer multiplied by gross margin. Skipping the margin term understates payback, since customers repay acquisition costs out of gross profit, not revenue.

#### What is the difference between CAC payback period and LTV:CAC?

CAC payback measures how fast you recover acquisition spend; LTV:CAC measures the total return on it. Payback is the harder metric to fudge because it uses observed revenue and margin, while LTV leans on a churn forecast.

#### Can a CAC payback period be too short?

Yes. A payback of two or three months with strong retention usually means you are underspending on acquisition. A competitor willing to wait longer for repayment can outbid you for the same customers.

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