Tool · Investor Sam Biz

Customer Acquisition Cost (CAC) Calculator

June 30, 2026 • By the Investor Sam Editorial Team • Reviewed by Berly Sam Varghese, Editor
Customer acquisition cost, or CAC, is what you spend on sales and marketing to win a single new customer. It is the denominator of almost every growth decision: if you do not know your CAC, you cannot tell whether an ad channel is profitable or whether you are overpaying for growth. This calculator divides your total acquisition spend over a period by the number of new customers it produced. Pair it with lifetime value to judge whether that spend is worth it.

Example: Total sales and marketing spend (period): 20000 $ · New customers acquired: 100 customers

Customer acquisition cost$200
Cost per acquired customer$200

Worked example

If you spent $20,000 on sales and marketing in a quarter and gained 100 new customers, your CAC is $20,000 divided by 100, or $200 per customer. On its own that number means little; it becomes powerful when you compare it to the lifetime value of a customer. If each customer is worth $800 over their lifetime, a $200 CAC is healthy; if they are worth $250, you are barely ahead.

Frequently asked questions

What spend should I include?

Everything that goes into winning customers: ad spend, marketing salaries and tools, sales commissions and salaries, and agency fees. Leaving costs out understates CAC and flatters your channels.

Over what period should I measure?

Match the spend and the customers to the same window, usually a month or quarter. Be mindful of lag: dollars spent this month may win customers next month, which can distort a single short period.

What is a good CAC?

There is no universal number; CAC only makes sense relative to lifetime value. The common rule of thumb is that a customer should be worth at least three times what it cost to acquire them.

How is CAC different from cost per lead?

Cost per lead measures spend per prospect; CAC measures spend per paying customer. Because only some leads convert, CAC is always higher than cost per lead and is the number that actually affects profit.

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Sources

Berly Sam Varghese · Editor, Investor Sam

Berly Sam Varghese is an engineer who treats money the way he treats any hard problem — something to be engineered, not gambled on. He funded years of education and built real financial stability the patient way, by living below his means and investing rather than borrowing. He writes for the person building something and trying to keep the finances sane. He reviews and approves every article on Investor Sam and checks the figures against primary sources before anything is published. More about our standards.