How to Calculate CAC, With Examples

How to calculate CAC comes down to one division, total acquisition cost divided by new customers, but the examples below show where the real decisions are: what goes in the cost, which customers go in the count, how to handle lags, and how to turn the answer into a limit you can use. This guide gives the formula, five worked examples with checked arithmetic, spreadsheet formulas and a short list of data sources and pitfalls. It supports unit economics and budgeting and forecasting, builds on customer acquisition cost, and leads to blended CAC vs. paid CAC and customer lifetime value.

The formula

CAC = (Marketing spend + Sales spend + Related costs) / New customers

Steps:

1. Choose the period (a month or quarter) and match spend to customers with any lag.
2. Add up acquisition costs: media, agencies, production, the acquisition share of salaries and commissions, tools and incentives.
3. Count new customers: first-time buyers or new subscribers, from the orders or billing system.
4. Divide.
5. Repeat by channel and segment.

Example 1: a simple ecommerce brand

In a month, the brand spends $60,000 on acquisition (media, creative, agency and tools) and wins 750 new customers.

CAC = 60,000 / 750 = $80.

If the same month had 1,200 orders in total, the other 450 orders came from returning customers and do not belong in the denominator. Using 1,200 would give $50, which understates CAC by 37.5 percent. Always count new customers, not orders.

Example 2: a B2B company

A quarter's costs: marketing programs $90,000, sales salaries and commissions $210,000, tools and travel $30,000. Total = $330,000. New customers won: 11.

CAC = 330,000 / 11 = $30,000.

Example 3: adjusting for the sales cycle

The B2B company above has a three-month average sales cycle, so customers won in Q2 reflect spend in Q1. Q1 spend was $330,000. Q2 spend was higher, at $360,000, because the company hired two sellers. Q2 produced 11 new customers.

• Same-period CAC: 360,000 / 11 = $32,727
• Lagged CAC: 330,000 / 11 = $30,000

The same-period figure is distorted by the extra hiring, which has not yet produced customers. The lagged figure matches cost to result. In a fast-growing sales team, the lag matters more, and the difference can be much larger. If the cycle is long, report a rolling twelve-month figure as well.

Example 4: by channel

A month of channel results for an ecommerce brand:

Blended CAC = 90,000 / 1,350 = $66.67. Paid CAC = 90,000 / 1,100 = $81.82 (paid channels only produced 1,100 customers: 600 + 400 + 100). Channel CACs of $50, $100 and $200 show that influencer is four times as expensive as search to acquire a customer, which may or may not be acceptable depending on the lifetime value of the customers each channel brings. See blended CAC vs. paid CAC.

Example 5: the maximum affordable CAC

CAC means little without a ceiling. Suppose contribution per order is $22 and a new customer places 1.8 orders on average in twelve months.

• Twelve-month contribution per customer = 22 × 1.8 = $39.60

If the goal is to recover CAC within twelve months, the maximum affordable CAC is $39.60. If you want a cushion for overhead and risk, such as a 1.5 to 1 return, the limit is 39.60 / 1.5 = $26.40. Compare the ceiling with actual CAC by channel. A channel above the ceiling is losing money on the first year of customers, and needs either higher repeat or lower cost. See LTV to CAC ratio.

Spreadsheet formulas

CAC:                   =TotalAcquisitionCost/NewCustomers
CAC by channel:        =SUMIFS(SpendRange,ChannelRange,A2)/SUMIFS(NewCustRange,ChannelRange,A2)
Rolling 3-month CAC:   =SUM(B2:B4)/SUM(C2:C4)
Lagged CAC:            =B2/C3
Max affordable CAC:    =ContributionPerOrder*OrdersPerCustomer/TargetRatio

Keep spend and customer data on a table sorted by date, with one row per channel and month, so that the formulas can be copied.

Data sources

Reconcile platform spend to the general ledger every month. Differences are common and often reveal unrecorded costs.

Pitfalls

• Counting orders or sessions as customers.
• Using only media spend while reporting the result as fully loaded.
• Ignoring time lags in launch, seasonal and enterprise sales.
• Relying on platform attribution without a sanity check against total new customers.
• Changing the definition between months.
• Comparing CAC to revenue instead of contribution.

Choosing between methods

Which version of the calculation you use depends on the question. Use the simple same-period formula for a quick monthly read on a stable business. Use the lagged version when spend is changing fast, when you launch a product, or when the sales cycle is longer than a month. Use a rolling three-month figure to smooth seasonality. Use channel CAC to compare the efficiency of channels, and treat it as an estimate that depends on attribution. Use the maximum affordable CAC as the decision rule, because a CAC figure without a limit to compare it with does not tell you whether to spend more or less.

Allocating salaries and shared costs

Salaries are usually the largest cost people forget. Suppose a growth team of four costs $36,000 a month in salaries and benefits. If the team spends 80 percent of its time on acquisition and 20 percent on retention, then the acquisition cost is 36,000 × 0.80 = $28,800. Add that to media and tool costs. Do the same for the sales team. It is better to be approximately right and consistent than precisely right once.

Edge cases that change the count

Free trials. If 1,000 people start a trial and 25 percent convert, then 250 become paying customers. With $50,000 of spend, CAC per paying customer is 50,000 / 250 = $200, while cost per trial is $50. Quote the one that matches the decision, and never mix them.

Reactivated customers. Someone who bought two years ago and returns after a campaign is a returning customer in most definitions. Decide a window, such as twelve months without a purchase, after which a returning buyer counts as new, and apply it consistently.

Refunded first orders. If a customer is refunded and never buys again, they were not really acquired. Some teams exclude them from the count, and others keep them to reflect the true cost of the attempt. Whichever you choose, apply the same rule to the contribution side.

Multiple purchases in the first period. One customer who places three orders in their first week is one new customer, not three.

A monthly routine

1. Reconcile ad platform spend to the ledger.
2. Allocate shared costs on the agreed basis.
3. Count first-time customers from the orders system.
4. Calculate blended, paid and channel CAC.
5. Compare each with the maximum affordable CAC.
6. Record the result with a note on what changed.

FAQs

How do you calculate CAC?

Divide total acquisition costs, including marketing and sales, by the number of new customers in the same period, adjusting for any lag.

What is the CAC formula for ecommerce?

Total marketing spend, including media, creative, agencies and tools, divided by first-time customers in the period.

How do you calculate CAC for B2B?

Add marketing programs, the marketing team, sales salaries and commissions, tools and travel, and divide by new customers won, using spend from one sales cycle earlier if the cycle is long.

What time period should I use?

A month for management, a quarter for smoothing, and a rolling view for businesses with lags or seasonality.

How do I know if my CAC is too high?

Compare it with the contribution each new customer generates over a defined period, usually through payback and the LTV to CAC ratio.