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CAC payback period calculator. How fast does a customer pay you back?

A free CAC payback period calculator that shows how many months it takes to earn back what you spent acquiring a customer. The metric that tells you how capital-efficient your growth really is.

The calculator

CAC payback period calculator, live.

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CAC payback period
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This calculator runs entirely in your browser. Nothing you enter is sent anywhere or stored. It is a quick estimate, not financial advice.

Why it matters

Reading your cac payback period right.

CAC payback period tells you how many months of margin-adjusted revenue it takes to earn back what you spent acquiring a customer. It is the clearest read on the capital efficiency of your growth. A short payback means you recover cash fast and can recycle it into more growth. A long payback ties up cash and strains runway, even if the customer turns a profit over time.

The margin adjustment matters. Paying back $9,000 of CAC at $750 a month sounds like 12 months but at 80% gross margin you only keep $600 of margin a month, so the real payback is 15 months. Always use gross profit, not revenue or you will systematically understate how long your money is tied up.

How to use it

How the cac payback period works.

01

Use fully loaded CAC

Include salaries, tools and overhead in CAC, not just media spend or the payback will look faster than it really is.

02

Find monthly ARPA

Take average monthly recurring revenue per account. Use the relevant segment if your segments differ a lot.

03

Adjust for gross margin

Multiply ARPA by gross margin to get monthly gross profit, then divide CAC by that. The result is the true payback in months.

Payback (months) = CAC / (ARPA x Gross margin)
CAC: fully loaded customer acquisition cost.
ARPA: average monthly revenue per account.
Gross margin: the share of revenue left after serving the customer. The denominator is monthly gross profit per customer.
Common questions

What people ask about the CAC payback period calculator.

What is CAC payback period?+

CAC payback period is the number of months it takes to recover the cost of acquiring a customer from the gross profit that customer generates. It measures the capital efficiency of growth: a short payback means you get your acquisition spend back quickly and can reinvest it, while a long payback ties up cash for longer. It is calculated by dividing CAC by the monthly gross profit per customer.

How do you calculate CAC payback period?+

Divide fully loaded customer acquisition cost by monthly gross profit per customer, where monthly gross profit is average revenue per account multiplied by gross margin. Using gross profit rather than revenue is essential, because you only keep the margin, not the full subscription price. A $9,000 CAC against $600 of monthly gross profit is a 15-month payback, not the 12 months the raw revenue would suggest.

What is a good CAC payback period for SaaS?+

For most B2B SaaS, 6 to 12 months is the healthy zone and under 6 months is excellent. Higher-ACV enterprise SaaS can tolerate 12 to 18 months because the deals are large and sticky but payback beyond 18 months strains cash even when customers are profitable in the end. The right benchmark depends on your funding and runway: well-capitalised companies can accept slower payback to grow faster.

Why does CAC payback matter more than LTV CAC ratio?+

They measure different things and both matter. LTV to CAC tells you whether a customer is worth more than they cost over their lifetime. CAC payback tells you how quickly you get your money back, which is about cash and capital efficiency rather than lifetime profit. A SaaS can have a great LTV to CAC ratio but a punishing payback period that ties up so much cash it constrains growth. Watch both.

How do I improve CAC payback period?+

Three levers: lower CAC, raise ARPA or improve gross margin. Lowering CAC through more efficient channels and better conversion shortens payback directly. Raising ARPA through pricing or expansion increases the monthly gross profit recovering the cost. Improving gross margin, often through more efficient infrastructure or support, increases the share of revenue that counts toward payback. For many SaaS, pricing and expansion move payback fastest.

SaaS CAC calculatorLTV:CAC ratioSaaS LTV calculatorSaaS marketing analytics

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