Free CAC (Customer Acquisition Cost) Calculator
Calculate fully loaded customer acquisition cost, ad-only CAC and a simple contribution-based payback estimate. Use advanced options and copy or download your results. Browser-based and no signup required.
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How to use the cac (customer acquisition cost) calculator
Calculate fully loaded customer acquisition cost, ad-only CAC and a simple contribution-based payback estimate. No signup required.
- Enter advertising, allocated acquisition salaries, software, agency and other acquisition spend for one period.
- Enter new paying customers acquired in that same period or cohort.
- Optionally enter average monthly gross contribution per customer for a simple payback estimate.
- Compare fully loaded CAC, ad-spend-only CAC and payback, then copy or download the calculation.
When a CAC calculation is worth doing
Knowing what it costs to win one new customer turns marketing from a gut feeling into a number you can compare month to month. It shows whether a new channel is earning its budget and whether raising prices or cutting spend should come first.
This calculator suits online store owners reviewing a holiday campaign, subscription founders preparing for a board meeting, agencies reporting results to a client, and freelancers deciding whether paid ads are worth trying at all. It gives three figures from one set of inputs: fully loaded CAC, ad-spend-only CAC and a simple payback period.
A worked example with real numbers
Suppose a small skincare brand spent the following in March: 12,000 on advertising, 4,500 as the share of a marketer's salary spent on acquisition, 600 on email and landing page software, 1,500 for an agency that made ad creative, and 400 on other costs such as promo samples. That totals 19,000. The brand gained 250 new paying customers in March.
Fully loaded CAC = 19,000 ÷ 250 = 76.00 per customer. Ad-spend-only CAC = 12,000 ÷ 250 = 48.00 per customer. The gap of 28.00 shows how much of each new customer's cost sits outside the ad platforms.
Now add an average gross contribution of 25 per customer per month. Payback = 76 ÷ 25 = 3.04 months. In plain terms, a typical new customer needs just over three months of purchases to repay what it cost to acquire them.
Understanding the three results
Fully loaded CAC adds every acquisition cost you enter, advertising, allocated salaries, software, agency fees and other costs, then divides by new paying customers from the same period. It is the fairer number for judging overall efficiency. Ad-spend-only CAC divides advertising alone by the same customer count, which is the figure most ad dashboards approximate.
Payback divides fully loaded CAC by monthly gross contribution, meaning revenue minus the direct costs of serving that customer, such as product cost, shipping and payment fees. It is not revenue. The payback figure assumes contribution stays flat and ignores churn and the time value of money, so treat it as a quick estimate.
These figures are general information. For pricing, fundraising or budget decisions, review them with an accountant or financial advisor who knows your business.
Common mistakes to avoid
Mixing periods is the biggest error. If ad spend is for March but customers are counted for the whole quarter, CAC looks far lower than it really is. Keep spend and customers from the same month or cohort.
Other frequent slips include counting returning buyers as new customers, entering a full salary when only part of that person's time goes to acquisition, and using revenue instead of gross contribution for payback. Each of these makes the business look healthier than it is. Also be careful in very small periods, where a few customers can swing CAC sharply.
Useful tips and limitations
- Allocate only the relevant portion of salaries and shared software costs.
- Payback assumes unchanged monthly contribution and excludes customer churn.
- Run the calculator once per channel, using only that channel's spend and customers, to see which source brings the cheapest customers.
- Compare fully loaded CAC with your customer lifetime value, since a business generally needs lifetime contribution well above CAC to stay profitable.
Common questions
How does fully loaded CAC differ from ad-only CAC?
Fully loaded CAC includes all acquisition costs you enter, while ad-only CAC divides advertising spend alone by new customers.
Should repeat buyers count as new customers in CAC?
No. Use newly acquired paying customers from the same period or cohort as the acquisition spend. Counting repeat buyers would understate acquisition cost.
What happens to customer acquisition cost when no customers were acquired?
The cost per new customer is undefined because the denominator is zero. Spend is still displayed, but no finite CAC or payback is reported.
What counts as gross contribution per customer?
It is the money a customer brings in each month after the direct costs of serving them, such as product cost, shipping and payment processing. Fixed overhead like rent is usually left out.
Why is no payback period shown?
Payback needs a CAC and a monthly contribution above zero. If either is missing or zero, the payback row is not calculated.
Should free trial signups count as customers?
Count only customers who became paying in the period. Trial signups that never pay would make your CAC look lower than it really is.
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