How to calculate customer acquisition cost

Count acquisition costs consistently

Include the sales and marketing expenses relevant to your definition: advertising, agency work, creative production and acquisition-related staff costs. A paid-channel CAC can use a narrower scope than company-wide blended CAC. Name the scope clearly so that two differently defined ratios are not compared as if identical.

Work through the arithmetic

Suppose acquisition expenses for a matched period total 6,000, and 120 first-time paying customers are acquired. CAC is 6,000 / 120 = 50. If the same expense brings only 80 new customers, CAC becomes 75. Spending zero can produce a zero result, but verify whether staff and other acquisition costs were omitted.

Do not substitute orders for customers

If those 120 customers place 180 orders, dividing by 180 gives 33.33 per order, not CAC. Repeat orders may improve lifetime contribution, but they do not represent 60 additional acquired customers. Define how refunds, test accounts and cancellations affect the new-customer count.

Allow for a long sales cycle

This month's spending may produce customers next month or later. A single-month CAC can look poor during growth and artificially low after spending is cut. Compare cohorts or a consistent longer period, and explain what can and cannot be attributed to the spending.

Compare against contribution and payback

A customer with 50 CAC and 20 monthly contribution takes 2.5 contribution-months to recover acquisition cost in a simple no-churn, no-discounting model. Actual payback depends on retention and payment timing. There is no universal safe CAC: fixed costs, cash availability and uncertainty also matter.

Separate channel CAC from blended CAC

Suppose one channel costs 2,000 and brings 80 new customers, while another costs 4,000 and brings 40. Channel CACs are 25 and 100. The combined CAC is total spending of 6,000 divided by 120 customers: 50. Averaging the two channel ratios would incorrectly give 62.50.

The combined figure can hide a poorly performing channel, while channel attribution can itself be uncertain. Keep the customer counts deduplicated so a person credited to two platforms is not counted as two new customers in the blended result.

Match the scope to the decision

An advertising-only CAC can help compare campaigns. A fully loaded acquisition calculation may also include sales labour, agency work, creative production and acquisition software. Both can be useful when clearly named, but comparing one with the other is misleading.

Decide how shared staff time is allocated and retain that rule between periods. Do not put ongoing service delivery into acquisition just because the same employee does both jobs. Separate the activities so you can understand whether the cost of winning or serving a customer has changed.

Use payback to understand the cash commitment

At CAC of 50, acquiring 120 customers requires 6,000 of acquisition spending. If each contributes 20 monthly and all remain active, the group contributes 2,400 per month before fixed overhead. The simple recovery period is 2.5 months, with actual receipt timing still separate.

Churn, introductory discounts and delayed payments can lengthen cash recovery. Before scaling, test a smaller contribution or fewer retained customers and inspect the cash available to fund acquisition. An attractive lifetime estimate does not ensure the business can finance the months before that value arrives.

Try the numbers yourself

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