Customer Acquisition Cost Calculator
This customer acquisition cost calculator divides your marketing spend by the new customers it brought in — then shows how fast that cost pays back using your average customer revenue and gross margin. CAC alone is just a cost; CAC against payback tells you whether your growth engine is sustainable. Run it per channel to find your cheapest growth.
All spend to acquire customers in the period: ads, agency, creative, tools.
Customers acquired by that spend — new only, not repeat buyers.
Average first-period revenue from one new customer (often close to AOV).
Gross margin % used to compute profit per customer for the payback estimate.
Customer acquisition cost
50
- Gross profit per customerAverage revenue × gross margin.
- 100
- Purchases to pay back CACHow many average purchases recover the acquisition cost.
- 0.5
- CAC as % of customer revenue
- 25%
How it was calculated
- CAC: $5000.00 ÷ 100 customers = $50.00.
- Profit per customer: $200.00 × 50% = $100.00.
- Payback: $50.00 ÷ $100.00 = 0.50 purchases.
How it works
CAC = total marketing spend ÷ new customers acquired. $5,000 for 100 customers is a $50 CAC.
Gross profit per customer = average revenue per customer × gross margin — the earnings each new customer contributes.
Payback in purchases = CAC ÷ gross profit per customer. A $50 CAC against $100 profit per customer pays back in half a purchase.
CAC as a percentage of customer revenue shows acquisition intensity at a glance; the lower, the more efficient the growth.
Worked examples
$5,000 spend, 100 customers, $200 revenue at 50% margin
CAC = $50. Profit per customer = $100. Payback = 0.5 purchases — the first order already covers acquisition twice over. CAC is 25% of customer revenue.
$12,000 spend, 150 customers, $300 revenue at 40% margin
CAC = $80. Profit per customer = $120. Payback = 0.67 purchases. CAC is 26.7% of revenue — healthy, provided customers actually return for that second purchase.
How to measure
- Include everything: ad spend plus agency fees, creative production and marketing software.
- Count only NEW customers — repeat purchases belong to retention, not acquisition.
- Attribute spend and customers to the same window; mismatched periods distort CAC badly.
- Compute CAC per channel separately; blended CAC hides that one channel may be 3x the others.
- Use gross profit (not revenue) for payback — revenue-based payback flatters expensive acquisition.
Assumptions & limitations
Planning estimate
- Payback assumes the average customer behaves like the average — cohorts vary.
- Organic and word-of-mouth customers acquired "for free" are excluded, which can flatter paid-channel CAC.
- Repeat-purchase behavior is not modeled beyond the payback-in-purchases estimate.
- This is a planning estimate, not financial advice.
Frequently asked questions
Divide all marketing and sales spend by the number of new customers acquired in the same period. $5,000 ÷ 100 customers = $50 CAC. Include agency fees and creative costs, not just ad platform spend.
Judge it against customer value, not in isolation: the classic rule is LTV:CAC of 3:1 or better. A $50 CAC is excellent against $500 lifetime value and terrible against $60. The payback row in this calculator gives you the quick read.
How long (or how many purchases) until a customer's gross profit repays what you spent acquiring them. Under 12 months — or under one purchase for ecommerce — is generally healthy; longer paybacks demand strong retention to be safe.
For a fully-loaded CAC, yes: marketing salaries, agency retainers, creative and software all acquire customers. For channel comparisons, a "paid CAC" using only direct spend is fine — just label which one you are quoting.
Common causes: ad auction competition, creative fatigue, broader (less qualified) targeting, or iOS-style tracking changes shrinking measured efficiency. Rising CAC with flat customer value compresses payback — fix targeting and creative before raising budgets.