The Metric That Decides Whether Growth Is Worth It
Revenue can climb while the business quietly bleeds — when every new customer costs more to win than they ever return. Customer acquisition cost (CAC) distills all marketing and sales spending into a single figure: the price of one new customer.
This free CAC calculator divides your total acquisition spend by genuinely new customers, then — if you enter average revenue per customer — computes the critical LTV:CAC ratio and tells you whether your acquisition engine is healthy, thin, or unsustainable. It also shows your healthy CAC ceiling: the most you should ever pay per customer.
Spend ÷ new customers → cost per customer
Please enter non-negative costs and a number of new customers greater than zero.
Costs and customer counts must cover the same period (a month or a quarter). The classic benchmark: CAC should be at most one-third of customer lifetime value. Blended CAC uses all spend; paid CAC isolates one channel.
How to Use This Calculator
- Enter total marketing costs — ads, content, SEO, tools, agency fees for the period.
- Enter total sales costs — salaries, commissions, CRM, and sales tools for the same period.
- Enter new customers acquired — first-time paying customers only, same period.
- Optionally add average revenue per customer to unlock the LTV:CAC verdict.
- Click Calculate CAC — read your cost per customer and health rating.
The Formula
LTV : CAC = Customer lifetime value ÷ CAC (healthy at 3:1 or better)
Worked example
A SaaS company spends $60,000 on marketing and $40,000 on sales in a quarter, winning 500 customers; average revenue per customer is $900:
- Total spend: $60,000 + $40,000 = $100,000.
- CAC = $100,000 ÷ 500 = $200 per customer.
- LTV:CAC = $900 ÷ $200 = 4.5 : 1 — comfortably above the 3:1 benchmark.
Who This Helps and Smart Tips
- Founders deciding whether to pour fuel on paid acquisition.
- Marketers comparing channel efficiency with one common yardstick.
- Investors sanity-checking unit economics before writing a check.
Tips
- Costs and customers must cover the same period — mixing months corrupts the ratio.
- Include fully-loaded costs: salaries and tools, not just ad spend.
- Count only new customers — renewals and upsells are retention, not acquisition.
- With long sales cycles, use rolling averages to smooth timing lags.
- To lower CAC: lift conversion rates, lean into referrals and content, tighten targeting.
The Cash-Flow Twin: CAC Payback Period
The LTV:CAC ratio says what a customer is ultimately worth; the payback period says how long your cash is out the door:
Take the worked example’s CAC of $200 and a customer paying $50 a month: payback = 200 ÷ 50 = 4 months before that customer has repaid what it cost to win them. For subscription businesses, under 12 months is generally considered strong, while drifting beyond 18 months starts to strain cash. Read the two metrics together — a healthy 3:1 ratio with a 20-month payback can still starve a growing company, because the money returns long after the next round of customers has to be bought.
Frequently Asked Questions
What is a good customer acquisition cost?
There is no universal number — $5 is terrible for a 99¢ app and superb for a mortgage broker. Judge CAC against lifetime value: keep it at or below one-third of LTV (a 3:1 ratio). Below that, growth funds itself; above it, growth consumes the business.
Should salaries be included in CAC?
Yes — include the share of salaries spent winning new business: salespeople’s time and the marketing hours devoted to acquisition. Exclude time spent serving existing customers; that belongs in cost of goods or support.
What is the difference between CAC and cost per lead?
Cost per lead counts inquiries; CAC counts paying customers. If one in five leads converts, CAC is at least five times the cost per lead before sales salaries are even added.
Can CAC be negative?
No. A negative CAC would mean you are paid to acquire customers, which contradicts the definition. If your math shows negative, check for sign errors in the inputs.
What is blended vs paid CAC?
Blended CAC uses all spend and all new customers — the whole engine’s efficiency. Paid CAC isolates one channel’s spend and its customers — the number to use when deciding whether to scale that channel.
How often should I calculate CAC?
Monthly for fast-moving businesses, quarterly for longer sales cycles. Track the trend: a rising CAC with flat LTV is the earliest signal that acquisition is breaking.
What is the difference between CAC and CPA?
CPA (cost per acquisition) prices a single action inside one campaign — a signup, a download, a lead. CAC is broader and stricter: all sales and marketing costs across every channel, divided by paying customers only. A cheap CPA can still hide an expensive CAC if few of those actions ever convert into customers.
Final Thoughts
CAC is the reality check every growth story needs. Compute it honestly — full costs, same period, new customers only — and let the LTV:CAC ratio tell you whether to scale, fix, or stop spending.
Model the other side of the equation with our compound interest calculator and plan spending with our sales tax calculator.
Try the CAC Calculator now
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