CAC stands for customer acquisition cost: the total sales and marketing spend required to acquire one new paying customer in a given period. You calculate it by dividing total sales and marketing costs by the number of new customers acquired over that same period. CAC is one of the core unit economics metrics, used alongside LTV and payback period to judge whether a business model actually works at scale.
Investors use CAC to test whether your growth is repeatable and profitable rather than simply fast. A company that grows revenue quickly but spends more to acquire a customer than that customer is worth is buying growth it cannot afford to keep.
CAC on its own tells you little. Investors always read it next to LTV, to see if you make money on each customer, and next to payback period, to see how fast you get your cash back. A rising CAC alongside flat LTV is often the first sign a channel is saturating or that competition is pushing up ad prices.
The basic formula is CAC = total sales and marketing spend divided by new customers acquired, measured over the same period, usually a month or a quarter.
Pick a definition and stay consistent. Paid CAC counts only paid media and directly attributable variable costs, divided by customers who came from paid channels. Blended CAC divides all sales and marketing spend, including salaries, tools, and content, by all new customers regardless of channel. Fully loaded CAC goes further still and adds sales and marketing salaries, software, contractors, and creative production tied to acquisition.
Blended CAC is almost always lower than paid CAC, since organic and referral customers cost close to nothing to acquire. Investors typically want to see both, and will ask which one you are quoting.
In Q2 your sales and marketing spend was $120,000 and you added 240 new paying customers. Blended CAC = $120,000 / 240 = $500 per customer.
Of that spend, $90,000 went to paid media and drove 180 of those customers. Paid CAC = $90,000 / 180 = $500 per customer as well in this case. In most companies paid CAC runs higher than blended CAC, since organic and referral customers pull the blended number down.
CAC varies more by customer segment than by company stage. SMB and self-serve SaaS typically runs $300 to $1,000 in paid CAC. Mid-market runs $1,000 to $4,000. Enterprise sales-led CAC commonly runs $5,000 to $20,000 or higher, since it includes longer sales cycles and higher-paid account executives.
The number to watch is not CAC in isolation but whether gross margin payback stays under roughly 12 to 15 months for SMB, 12 to 18 months for mid-market, and 18 to 24 months for enterprise. A high CAC can still be healthy if deal size and retention support it.
Quoting paid CAC in one meeting and blended CAC in the next without saying which is which. Investors catch this quickly and it damages trust in every other number you show.
Counting free trial signups as acquired customers instead of only paying customers. This inflates the denominator and makes CAC look artificially low.
Leaving out referral fees, discounts, and credits given to close a deal, and failing to separate one-off enterprise pilots from your core sales motion.
Put CAC on your financials or traction slide next to gross margin payback and LTV:CAC, with a footnote stating exactly what is included. For example: Blended CAC $500, gross margin payback 12.5 months, LTV:CAC 3.8x.
Showing the trend over the last two or three quarters is more convincing than a single snapshot. A CAC that stays flat or falls as you scale spend is a strong signal that your channels are not just working, they are working at increasing scale.
Includes all channels and costs. Smooths channel noise, useful for board-level tracking.
Use for paid channel efficiency. Excludes salaries and organic demand.
Common investor ask. Be explicit about what is included.
Looking for investors?
Browse 1,500+ investors filtered by stage, sector, country, and check size.
Explore the investor directory