Glossary
What is Customer Acquisition Cost? Definition
June 4, 2026
The customer acquisition cost (abbreviated as CAC) measures the average amount spent to acquire a new paying customer over a given period. In e-commerce, it is used to assess whether customer acquisition is profitable in relation to the margin of the first purchase and the customer lifetime value (CLV).
Summary
Definition: acquisition cost, CAC and CPA
Customer acquisition cost answers: "How much does a first-time customer cost me, on average?"
Standard formula:
Customer acquisition cost = Acquisition-related spend ÷ Number of new customers (same period)
Example: €9,000 acquisition spend in one month, 300 new clients → acquisition cost = €30 per customer.
Useful distinctions. Customer acquisition cost vs CAC: same indicator; CAC is the English acronym used in DTC marketing and investment. Customer acquisition cost vs customer acquisition: acquisition describes the actions (SEO, ads); acquisition cost measures the price. Acquisition cost vs CPA (Cost Per Acquisition): advertising CPA is often the cost per order or ads conversion, not always per new customer.
In the same spirit, Acquisition cost vs CPC: cost per click; many clicks do not become customers. Paid acquisition cost vs blended cost: paid only (Meta, Google) vs all channels including SEO and email converting new customers. Acquisition cost vs ROAS: ROAS = revenue ÷ ad spend; acquisition cost divides by the number of customers, not revenue.
Set the definition of new customer internally (first lifetime purchase, return after 12 months of inactivity, etc.) for comparable figures month after month.
Why customer acquisition cost is important
Without measuring this cost, a store can show growing revenue while losing money on each new customer.
The essential points to remember are as follows. Profitability: compare to the gross profit of the first purchase and to the CLV. Marketing budget: forecast how much to invest for X new customers. Channel arbitrage: Meta, Google, influence, and marketplaces have different acquisition costs. Pricing and promos: an acquisition coupon reduces the margin; this must be factored into the actual cost. Cash flow: a high acquisition cost with slow repeat purchases puts a strain on cash. Scale: increasing the ads budget without controlling the acquisition cost dilutes the margin.
Reference indicator: CLV ÷ acquisition cost ratio (often targeted at > 3 over the long term, varying by sector and cash flow). A low cost with a zero CLV (no repeat purchases) remains a dead end.
Measure acquisition cost on Shopify
Shopify does not always natively label "acquisition cost"; build the indicator by cross-referencing. Shopify Analytics: new vs. returning customers, sales by channel (Shopify Help Center). Ad platforms: spend and conversions by campaign. GA4: acquisition by source, imported costs if connected. Spreadsheet / BI: monthly consolidation (e-commerce analytics).
Tips. UTMs on every campaign link. Same attribution window as your ad reports. Export new customers by month (Reports > Customers). Separate paid and blended acquisition costs (organic dilutes blended).
Attribution apps (Triple Whale, Northbeam) help post-iOS, but the "new customer" rule remains your business choice. For detailed CAC formulas by channel, see the CAC sheet.
In summary
The essential points to remember are as follows. Customer Acquisition Cost = acquisition spend ÷ new customers. Equivalent to CAC; distinct from acquisition (actions) and CPA (conversion ads). To be cross-referenced with margin, CLV, and cost per channel. Shopify + ads + GA4 + defined "new customer" rule. Monthly tracking; optimize conversion and repeat for profitability.
Associated terms, FAQ, and resources
Associated terms
CAC: acronym and detailed calculation.
Customer acquisition: strategy and channels.
CLV: CLV / acquisition cost ratio.
ROAS: ad return, complementary metric.
AOV: average order value of new customers.
FAQ
Customer acquisition cost and CAC: what is the difference?
None in a metric sense: it is the same formula. "Coût d'acquisition client" is the full French formulation; CAC is the common English acronym in e-commerce.
What acquisition cost is acceptable?
It must remain lower than the margin and the CLV generated. No universal benchmark: depends on the sector, the order value, the repeat purchase rate, and cash flow.
Should SEO be included in the acquisition cost?
Organic traffic has no direct media cost, but copywriting and SEO tools do have a cost. Many calculate a separate paid acquisition cost and a blended cost that includes content.
How to reduce the acquisition cost?
Improve the conversion rate, refine ad targeting, test creatives, develop SEO/email (customers without paid media), and build loyalty to amortize the cost over multiple purchases.
Go further
Sources: Shopify Analytics client reports, DTC metric tips. CLV/acquisition cost ratios: adapt to your accounting and cash flow.
Enzo
13 May 2026
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