Customer acquisition cost formula and CAC calculator: blended CAC and LTV:CAC ratio

How do you calculate customer acquisition cost?

You calculate customer acquisition cost by adding every sales and marketing cost for a period and dividing by the number of new customers won in that same period. If a quarter cost $40,000 in marketing and $20,000 in sales and produced 500 new customers, CAC is $60,000 / 500 = $120. Match the two windows or the answer is meaningless.

Pick a period long enough to smooth out noise. Most teams run CAC monthly for operations and quarterly for board reporting. The one discipline that matters is consistency: change the inputs from one month to the next and you have not measured a trend, you have measured your own bookkeeping.

What is the customer acquisition cost formula?

The customer acquisition cost formula is CAC = (sales spend + marketing spend) / new customers acquired. That is the whole equation. Everything difficult about CAC lives in deciding what goes into the numerator and which customers count in the denominator, not in the arithmetic.

A narrower variant, paid CAC, divides paid media spend only by the customers those paid channels produced. It is the number that tells you whether advertising pays for itself, and it runs higher than blended CAC because it strips out the customers who arrived through organic search, referral, or email.

What should be included in customer acquisition cost?

Include everything spent to turn a stranger into a customer: ad spend, agency and freelancer fees, content production, marketing and sales salaries, commissions and bonuses, and the software those teams use. A CAC built from ad spend alone will flatter you, sometimes by more than half, because for most companies people cost more than media.

Leave out the costs of serving customers you already have. Customer support, account management, retention campaigns, and product development belong to a different question. Overhead such as rent and general administration is usually excluded too, since it would be spent whether or not you acquired anyone.

What is a good customer acquisition cost?

A good customer acquisition cost is one comfortably below what a customer is worth to you, which is why CAC is judged as a ratio rather than a dollar figure. The common threshold is an LTV:CAC of 3:1, meaning a customer generates at least three dollars of gross-margin lifetime value for every dollar spent winning them. A $1,400 CAC is excellent for enterprise software and ruinous for a $40 ecommerce order.

Published benchmarks put the spread in perspective. First Page Sage, working from agency client data updated in January 2026, reports combined B2B CAC of $86 in ecommerce, $239 in B2B SaaS, $749 in legal services, and $1,143 in education. Treat those as orientation rather than targets, and read our breakdown of average customer acquisition cost by industry for the organic and paid splits and why the same industry gets quoted at wildly different numbers.

What is the difference between blended CAC and paid CAC?

Blended CAC divides all acquisition spend by all new customers, whatever brought them in. Paid CAC divides paid media spend by only the customers attributed to paid channels. Blended CAC answers what growth costs the business; paid CAC answers whether the ad account is working. Both are legitimate and they are not interchangeable.

The mistake to avoid is comparing your blended CAC against someone else's paid CAC, or quietly switching between the two as the numbers move in your favor. Report both, label them, and keep the definitions fixed. Our guide to calculating blended CAC walks through the worked examples in full.

How do you calculate the LTV:CAC ratio?

Divide average customer lifetime value by customer acquisition cost. A $480 lifetime value against a $120 CAC gives 4:1. Use gross-margin lifetime value rather than gross revenue, otherwise a low-margin business will look far healthier than it is, since the revenue a customer generates is not money you keep. If you do not have a lifetime value figure yet, the customer lifetime value calculator works it out from order value, purchase frequency, lifespan, and margin.

Pair the ratio with payback period, because the two answer different questions. A 5:1 ratio spread over four years is a cash-flow problem even though the ratio looks strong. Our pages on the LTV:CAC ratio and CAC payback period cover both, and if the number is coming out worse than you want, the practical levers are in reducing customer acquisition cost.

Why is CAC harder to calculate across multiple ad platforms?

Because each ad platform counts conversions its own way and claims credit for the same customer. Google Ads books a conversion to the click date and allows windows up to 90 days; Meta offers 1, 7, or 28 day click windows; TikTok caps at 7 days. Add up the customers each platform reports and you will exceed the number of people who actually bought, which drags your calculated CAC below reality.

That is why blended CAC is the safer operating number: dividing total spend by the customers your billing system actually recorded cannot be inflated by overlapping attribution. It is the same logic behind blended ROAS and MER, and the reason platform-reported figures and store-reported figures never quite match.

MixedMetrics does this continuously. Read-only connectors pull spend from Google Ads, Meta, and TikTok alongside real customers and revenue from Shopify and Stripe, then compute blended CAC, blended ROAS, MER, and LTV:CAC on one board that updates daily. You can also run the reverse check with the ROAS calculator.