CAC
GeneralCustomer Acquisition Cost
The total cost of acquiring a new customer, including all sales and marketing expenses ā the foundational unit economics metric for any business.
Written by Anurag Rath Ā· Reviewed by the thecalcu.com team Ā· Last updated June 20, 2026
What is CAC?
CAC (Customer Acquisition Cost) is the total cost a business incurs to acquire one new paying customer, across all sales and marketing channels. It is the foundational unit economics metric, businesses must understand how much it costs to get a customer before they can determine whether their business model is profitable and scalable.
CAC = Total Sales & Marketing Expense / Number of New Customers Acquired
CAC is valuable in isolation but most meaningful in relation to CLV (Customer Lifetime Value). If you spend ā¹1,000 to acquire a customer who generates ā¹5,000 in lifetime revenue, the economics are strong. If you spend ā¹1,000 to acquire a customer who generates ā¹800, you're destroying value with each sale.
Formula
CAC = Total Sales & Marketing Spend / New Customers Acquired
CAC Payback Period = CAC / Monthly Revenue Per Customer
CLV:CAC Ratio = Customer Lifetime Value / CAC
Healthy benchmarks:
- CLV:CAC ratio ā„ 3:1
- CAC payback period ā¤ 12ā18 months
Worked Example
A B2B SaaS company's quarterly numbers:
| Expense | Amount |
|---|---|
| Paid ads | ā¹8,00,000 |
| Agency fees | ā¹1,50,000 |
| Sales team (salaries + commissions) | ā¹12,00,000 |
| Marketing team salaries | ā¹5,00,000 |
| Tools (CRM, automation) | ā¹80,000 |
| Total S&M Spend | ā¹27,30,000 |
New customers acquired: 91
CAC = ā¹27,30,000 / 91 = ā¹30,000 per customer
Average annual contract value (ACV): ā¹96,000 (ā¹8,000/month) Monthly gross margin per customer: ā¹5,600 (70% gross margin)
CAC Payback = ā¹30,000 / ā¹5,600 = 5.4 months ā (healthy) CLV (at 2% monthly churn, 50 months average lifetime): ā¹5,600 Ć 50 = ā¹2,80,000 CLV:CAC = ā¹2,80,000 / ā¹30,000 = 9.3:1 ā (excellent)
Use the CAC calculator and CLV calculator to model your business.
Key Things to Know
- CAC payback period matters for cash flow: Even a great CAC:CLV ratio doesn't help if the payback period is 3 years, the business needs to fund 3 years of customer service before recovering the acquisition cost. Fast-growing businesses with long payback periods need significant external capital. Investors scrutinise payback period as a proxy for capital efficiency.
- Channel-level CAC drives investment allocation: Not all channels have equal CAC. Organic search (SEO content) typically has low marginal CAC once the content is established. Paid search has predictable but higher CAC. Referrals and word-of-mouth have the lowest CAC. By tracking channel CAC, businesses can systematically shift spend toward efficient channels and away from expensive ones.
- Churn rate and CAC interaction: High churn rate forces you to acquire more customers just to maintain the same revenue base, dramatically increasing effective CAC burden. If you churn 5% of customers monthly, you need to replace 60% of your customer base annually just to stay flat. Reducing churn by 1% often has more economic impact than reducing CAC by 10%.
- ROAS vs CAC: ROAS measures revenue efficiency of ad spend. CAC measures the total cost to acquire a customer across all channels. ROAS doesn't account for product costs; CAC doesn't measure revenue. Use ROAS to optimise advertising; use CAC:CLV to evaluate overall business unit economics.
- New vs expansion revenue: If existing customers expand their spending (buy more, upgrade tier), should this be counted against CAC? The answer matters: if expansion revenue is counted, effective CAC appears lower than actual new customer acquisition cost. Standard practice: CAC should only count new customer acquisition costs; expansion revenue is tracked separately as Net Revenue Retention (NRR).