Free Tool
Customer Acquisition Cost Calculator
Customer acquisition cost is one division — but only if the two numbers come from the same period. Spend from January divided by customers from March is not CAC, it is a coincidence. This calculator keeps the period matched.
Planning estimate, not financial advice. CAC is a planning figure from inputs you enter. No 'good CAC' benchmark is quoted here — what is good depends on what a customer is worth to you. All figures on this page are estimates or scenarios for planning purposes only. They are not financial, tax or legal advice, and no earnings are promised. Read the full financial disclaimer.
What this tool does
Enter the total sales and marketing cost for a period and the number of new customers gained in that same period. The calculator returns CAC: cost divided by customers. If you also enter the paid portion separately (advertising spend and the customers it brought), it splits the result into paid CAC and organic CAC — the cost of customers who arrived without advertising — so you can see which channel is actually doing the work.
The period-matching rule is the whole point of this page. A store that spent $2,400 in March but counts customers acquired in April is mixing two different funnels: advertising takes time to convert, and a mismatched period makes CAC look better or worse than it is for no reason. Use the same month, quarter or year for both numbers, and say which one it was.
CAC means little on its own. Its partner number is lifetime value: a $20 CAC is expensive for a customer worth $25 and cheap for a customer worth $200. The lifetime value calculator on this site computes that side, and the two pages cross-link for exactly that reason.
Try it
Waiting. Enter spend and new customers from the same period and press Calculate CAC. The two numbers must cover the same period, or the result means nothing.
How it works
CAC equals total sales and marketing cost in a period divided by new customers in that same period. Paid CAC is paid advertising spend divided by customers from paid advertising. Organic CAC is the remaining spend (total minus paid) divided by the remaining customers (total minus paid). All three are the same formula applied to different slices of the same period.
What counts as "sales and marketing cost" is a decision the page leaves visible: it should include advertising spend, tool subscriptions used to acquire customers, and the time cost of the people doing the acquiring if you count it — but it must be the same basket every time you measure, or month-to-month comparisons are meaningless. The example below counts advertising plus tool costs and no time cost, and says so.
Assumptions and limitations
CAC is a period average, not a per-customer fact: some customers cost $2 and some cost $200, and the average hides the spread. It does not model the delay between spend and customer (an ad in March may convert in May), repeat customers (only new customers belong in the denominator), or customers who churn immediately. It says nothing about whether the CAC is worth paying — that needs the lifetime value of the customer, which is a separate calculation.
- Period-matched inputs are required: spend and customers must cover the same period, or the result is meaningless. The page cannot check this — you have to.
- Zero new customers means CAC is undefined, not zero — the calculator says so instead of dividing by zero.
- Paid customers cannot exceed total customers, and paid spend cannot exceed total spend; both are rejected as input errors.
- No "good CAC" benchmark is quoted anywhere on this page, because a good CAC depends entirely on what a customer is worth to your business.
Worked example
Example (illustrative inputs, not a real store's figures). A store spends $2,400 on sales and marketing in a month (advertising plus tools, no time cost counted) and gains 120 new customers in the same month. CAC: $2,400 ÷ 120 = $20.00 per customer. Of that, $1,800 of advertising brought 60 customers: paid CAC $1,800 ÷ 60 = $30.00. The remaining $600 brought the other 60 customers: organic CAC $600 ÷ 60 = $10.00. The blended $20 hides the split: paid customers cost three times what organic customers cost, which is the decision the store actually has to make.
Frequently asked questions
What counts as sales and marketing cost for CAC?
Advertising spend, the tools you use to acquire customers, and the time cost of the people doing the acquiring — if you count it. The exact basket matters less than consistency: use the same basket every time you measure, or month-to-month comparisons are meaningless. Say which basket you used when you quote the number.
Why must spend and customers come from the same period?
Because advertising takes time to convert. Spend from March divided by customers from April mixes two funnels and the result is not CAC — it is a coincidence that happens to have a dollar sign. Use the same month, quarter or year for both numbers.
How do I know if my CAC is good?
Compare it with what a customer is worth to you — the lifetime value. A $20 CAC is expensive for a customer worth $25 and cheap for a customer worth $200. There is no universal 'good CAC' number, which is why this page never quotes one. Run the lifetime value calculator and compare the two.
What is the difference between blended and paid CAC?
Blended CAC is total spend divided by all new customers. Paid CAC is advertising spend divided by the customers advertising brought. The split shows whether growth is bought or earned: if paid CAC is far above blended CAC, organic channels are doing the efficient work and advertising is the expensive part.
Should repeat customers count in CAC?
No. CAC is the cost of acquiring a new customer, so the denominator is new customers only. Repeat purchases belong in lifetime value, not in CAC — mixing them understates the cost of growth.
Why does the calculator refuse zero new customers?
Because dividing spend by zero customers is undefined, not zero. A month with spend and no new customers has an infinite CAC in the strict sense — and in the practical sense it means the spend produced nothing, which the error message says more honestly than a number would.