Customer Acquisition Cost: How to Calculate CAC and What to Include

Customer acquisition cost is your total sales and marketing spend divided by the number of new customers that spend produced. Spend $180,000 in a quarter, sign 60 new customers, and your CAC is $3,000.

The arithmetic is not the hard part. The hard part is deciding what belongs in the numerator, and most teams decide it too narrowly — which is why the CAC on the board slide is often half the CAC the business is actually paying. This piece covers what to include, three ways to run the same period, and why payback period matters more than the ratio everyone quotes.

What is customer acquisition cost?

Customer acquisition cost is the average amount a business spends to win one new customer over a defined period.

CAC = Total sales and marketing costs ÷ New customers acquired


Both halves need a fixed window — a quarter, a year — and both halves must describe the same window. The metric exists to answer one question: can you afford to keep buying customers at this price? Everything else it gets used for, from channel budgeting to board reporting, is downstream of that.

What counts as an acquisition cost, and what doesn't

This is where CAC calculations diverge, and it is worth being strict.

Include

CostWhyPaid media and advertisingDirect acquisition spendSalaries for sales and marketing headcountUsually the largest single input, and the most commonly omittedCommissions and bonuses on new businessVariable cost of closingAgencies, contractors, freelancersOutsourced acquisition workMarketing and sales softwareCRM, automation, enrichment, analyticsEvents, sponsorships, content productionAcquisition spend with a longer lagDiscounts given to win a dealA discount is acquisition cost paid in revenue rather than cash

Exclude

CostWhyCustomer success and support after onboardingRetention, not acquisitionExpansion and upsell activityThose are not new customersProduct engineeringBuilding the thing is not selling itGeneral overhead, finance, HR, officeNot attributable to acquisition

The ones that cause arguments

Four costs sit on the line, and the answer is the same for all of them.

Founder and executive selling time. If a founder spends half their week in sales calls, half a founder salary is acquisition cost. Leaving it out is the single most common reason early-stage CAC looks impossibly good.

Brand and PR. Spend intended to make future selling easier is still acquisition spend. It has a longer lag, which argues for measuring it over a longer window, not for excluding it.

Partner and affiliate commissions. If the commission is paid for a new customer, it is acquisition cost, whatever line it sits on in the P&L.

Free-trial infrastructure. The compute and support consumed by people who never convert is a cost of acquiring the ones who do.

The test: if you stopped trying to acquire new customers tomorrow, would this cost fall? If yes, it belongs in CAC. Apply it to anything not listed above and you will get a defensible answer.

How to calculate CAC three ways on the same numbers

The word "CAC" is used for at least three different figures. The gap between them is not academic — it is usually the difference between a business that looks efficient and one that doesn't.

Take one quarter:

InputAmountPaid media$60,000Sales salaries (3 AEs, 1 SDR)$75,000Marketing salaries (2 FTE)$38,000Commissions on new business$14,000Agency and contractors$12,000Sales and marketing software$9,000Founder selling time (0.4 FTE)$11,000New customers acquired60New customers from paid media22

Three calculations follow.

Blended CAC — all acquisition spend, all new customers.(60,000 + 75,000 + 38,000 + 14,000 + 12,000 + 9,000 + 11,000) ÷ 60 = $3,650

Paid CAC — paid media only, divided by customers attributable to paid.60,000 ÷ 22 = $2,727

Fully loaded CAC — everything, including the costs most teams leave out. In this example blended and fully loaded are the same figure, because founder time and software are already in. Strip those two out, as many teams do, and you get:(60,000 + 75,000 + 38,000 + 14,000 + 12,000) ÷ 60 = $3,317

Same quarter. $2,727, $3,317 or $3,650, a spread of a third, depending entirely on which costs were counted.

Which to use:

• Board reporting and fundraising — fully loaded. Anyone doing diligence will rebuild it this way regardless, and a number that moves upward under scrutiny costs you credibility.
• Channel decisions — paid CAC, per channel. Blended tells you nothing about whether to increase a specific budget.
• Trend tracking — pick one and never change it. The direction matters more than the absolute.

What a good CAC looks like, by motion

There is no absolute benchmark, because CAC scales with contract value. A $3,650 CAC is excellent against a $40,000 annual contract and fatal against a $500 one.

The convention is to judge CAC against what a customer is worth rather than in isolation, using the LTV:CAC ratio. Wall Street Prep's 2024 analysis identifies 3.0x as the standard target — lifetime value at least three times acquisition cost.

Two things that ratio hides.

A ratio above 5:1 is usually read as a triumph. More often it means underinvestment: the business could profitably acquire more customers and isn't. Below 1:1 means each new customer destroys value, and growth makes the problem worse rather than better.

And a healthy ratio says nothing about when the money comes back. Which is the next section.

CAC payback period

Payback period is the number of months of gross profit needed to recover the cost of acquiring a customer.

CAC payback (months) = CAC ÷ (Monthly recurring revenue per customer × Gross margin %)


Continuing the example. Sixty customers at $850 MRR each, gross margin 78%:

3,650 ÷ (850 × 0.78) = 3,650 ÷ 663 = 5.5 months

Five and a half months to recover acquisition cost, after which that customer contributes profit.

This matters more than the ratio for one reason: LTV is a projection and payback is not. A 3:1 ratio built on an assumed five-year lifespan is a forecast. Payback is arithmetic on money you have already spent and revenue you are already collecting.

A business with a 4:1 ratio and 26-month payback is financing two years of customer acquisition out of working capital. It can run out of cash while every efficiency metric on the dashboard looks healthy. Payback periods under roughly 12 months are treated as comfortable for smaller contracts, with 18 to 24 months tolerated in enterprise sales where contracts are longer and stickier — though these are working conventions rather than researched thresholds, and yours should be set against your own runway.

Five ways CAC gets miscalculated

Renewals counted as new customers. Inflates the denominator, deflates CAC, and the error grows as the base grows. Count only first-time paying customers.

Sales salaries left out. Usually the largest input. Teams that count only media spend are typically reporting a CAC less than half the real figure.

Self-serve and sales-led averaged together. A business with a $200 self-serve motion and a $40,000 enterprise motion has two CACs. The blended figure describes neither and hides that one may be subsidising the other.

Long cycles attributed to the month of close. A customer who closed in March after a seven-month cycle was acquired with spend from the previous August. Comparing March spend to March closes measures nothing. Either lag the spend or use a window longer than your sales cycle.

Organic treated as free. Content, SEO and social have a cost — salaries, tooling, production. Excluding them makes organic look infinitely efficient and distorts every channel comparison built on top.

A worked audit: where the missing third usually hides

The following is a modeled scenario built from the cost categories above, not a client account. The figures are illustrative.

Take a 40-person B2B SaaS company selling to mid-market, reporting CAC of $1,850 and treating that as healthy against a $28,000 average contract value.

That $1,850 came from dividing paid media by new logos. Rebuilding it with the inclusion rule from earlier adds four things:

LineQuarterlyWhy it was excludedReported basis (paid media only)$148,000—Sales salaries, 4 FTE$96,000Sat in payroll, never allocatedMarketing salaries, 2 FTE$41,000SameFounder selling time, 0.5 FTE$17,000Not considered a cost at allPartner commissions$12,000Booked as cost of revenueFully loaded$314,000

Against 80 new customers, the reported $1,850 becomes $3,925 — slightly more than double.

The LTV:CAC ratio moves with it. At a $28,000 ACV, 76% gross margin and a three-year average life, lifetime value is about $63,800. Against $1,850 that is 34:1, a figure that should have prompted suspicion rather than confidence. Against $3,925 it is 16:1 — still strong, and still suggesting the business is underinvesting in acquisition rather than overspending.

Which is the point. The corrected number did not reveal a problem; it revealed unused headroom. A company that believes its CAC is $1,850 and is nervous about raising it will underspend. One that knows it is $3,925 and that the ratio still clears 15:1 can justify doubling acquisition spend.

The error direction matters here: understating CAC usually reads as good news, which is exactly why it goes unchallenged.

How to reduce CAC without starving growth

Every lever below buys something and costs something. The trade-off is the point.

Conversion rate before traffic. Doubling landing page conversion halves paid CAC with no extra spend. It is the cheapest lever and the first to check. The cost is engineering and research time that could have gone to product.

Channel mix. Shifting budget toward lower-CAC channels works until those channels saturate. Watch marginal CAC, not average — the cost of the next customer from a channel, which rises as you scale it. Building a mix that holds up as you scale is its own exercise, covered in how to build a SaaS demand generation strategy.

Sales cycle length. Shorter cycles mean each rep closes more, spreading fixed salary cost across more customers. Usually achieved by qualifying harder, which means turning away deals.

Pricing and packaging. Raising price does not reduce CAC but improves everything CAC is judged against — payback shortens, ratio improves. The cost is conversion rate, and sometimes segment fit.

Retention feeding referral. The cheapest customer is one an existing customer brings. This is real but slow, and it is a retention program wearing an acquisition label.

What does not work: cutting acquisition spend to make the number look better. CAC falls, new customers fall faster, and the business shrinks while the dashboard improves.

What to do with the number

Recalculate CAC fully loaded, including salaries and founder selling time. Split it by motion rather than reporting one blended figure. Then track the trend rather than the absolute — a CAC rising 15% a quarter tells you something a single number never will.

If your CAC has never been rebuilt from the ground up, it is probably lower on the slide than it is in the bank.

For companies where organic search is a material acquisition channel, the same discipline applies to what that channel actually costs — see our approach to B2B SaaS SEO.