Customer acquisition cost answers the most dangerous question in marketing: what did each new customer cost us? This CAC calculator takes it one step further than a single division — it breaks the answer down by channel, so you can see that your paid social wins customers at one price and your paid search at another, and then blends them into the single CAC figure you should compare with your customer lifetime value.
Enter spend and new customers per channel for the same period; leave channels you do not use at zero. ¿Trabajas en español? La versión en español incluye el LTV y el ratio en la misma página: Calcular Costo de Adquisición de Cliente CAC.
The formula — and what counts as “spend”
CAC = total acquisition spend ÷ new customers acquired, over the same period. The honest version of “spend” is fully loaded: ad spend, yes, but also the tools, the freelancer or agency fees, and the share of salaries spent on acquisition. A CAC built on ad spend alone always looks better than the truth and leads to scaling channels that actually lose money. Whichever definition you choose, keep it constant: a CAC you can compare month over month beats a theoretically perfect one you compute differently each time. Count only new customers in the denominator — repeat orders belong in revenue, not in acquisition.
Worked example
Paid social: $1,000 spent, 50 new customers → CAC $20.00. Paid search: $600 spent, 20 new customers → CAC $30.00. Blended: $1,600 ÷ 70 customers = $22.86. The blended figure is the one to set against LTV; the per-channel figures are the ones to act on. Here they say search customers cost 50% more than social customers — which is fine if search customers also spend more or stay longer, and a warning if they behave identically.
What to do with the number
Three decisions run on CAC. First, channel budgets: shift spend towards channels whose CAC is below your blended figure, cautiously — cheap channels usually saturate first. Second, pricing and payback: CAC divided by the monthly gross profit per customer gives the months you wait to earn the acquisition cost back; long payback is a cash-flow problem even when the eventual profit is fine. Third, the LTV comparison: the common rule of thumb is that lifetime value should be at least about 3× CAC — a rule of thumb, not a law of nature, and the dedicated LTV:CAC calculator linked below explores the bands.
Limits
Attribution is the soft spot: a customer who saw a social ad, searched your brand and bought through search gets credited to whichever model you use, and every model lies a little. Small numbers also swing wildly — a channel with 3 customers has a CAC that one extra sale halves. Use this grid on a month of data at minimum, and treat big channel differences as questions to investigate, not verdicts.
Blended, paid-only, or fully loaded?
Three CACs circulate in most businesses and endless confusion comes from mixing them. Paid CAC counts only media spend and is useful for judging campaigns against each other. Fully loaded CAC adds tools, fees and people, and is the only one that belongs next to LTV. Blended CAC — total acquisition spend divided by all new customers, including the ones who arrived free through search, referrals and word of mouth — flatters the business and hides dying channels inside a healthy-looking average; it is useful for overall planning and dangerous for channel decisions. This grid computes per-channel CACs and their paid blend across the channels you fill in. Whichever you report, label it, and never compare one month’s fully loaded figure with another month’s paid-only one.
Related tools
Versión en español: Calcular Costo de Adquisición de Cliente CAC — Con ratio LTV:CAC incluido · LTV Calculator · LTV:CAC Ratio Calculator.
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