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Customer Acquisition Cost (CAC) is the total sales and marketing spend required to acquire one new paying customer. It's one of the core SaaS unit economics metrics.
The CAC formula
CAC = Total Sales & Marketing Spend ÷ New Customers Acquired
At $37,000/month in total S&M spend acquiring 50 customers: - CAC = $37,000 ÷ 50 = $740
What to include in CAC
Include all costs that exist because of your acquisition efforts:
| Include | Exclude |
|---|---|
| Paid ads (Google, Meta, LinkedIn) | Product development |
| Sales team salaries + commissions | General & administrative |
| Marketing team salaries | Customer success (post-sale) |
| CRM, ad tools, marketing automation | Hosting & infrastructure |
| Content creation costs | Support costs |
Many founders undercount CAC by excluding sales salaries or tools, making the metric look better than it is. Blended CAC includes everything.
CAC payback period
The most actionable CAC metric is payback period — how many months until you recover the acquisition cost from a single customer's gross profit.
CAC Payback = CAC ÷ (Monthly ARPU × Gross Margin %)
At $740 CAC, $99 ARPU (Average Revenue Per User), 75% gross margin: - Monthly gross profit per customer = $99 × 0.75 = $74.25 - Payback = $740 ÷ $74.25 = 9.97 months
CAC benchmarks by stage
| Stage | Acceptable payback | Notes |
|---|---|---|
| Seed / early stage | < 18 months | Still figuring out channels |
| Series A | < 12 months | Channels identified, optimizing |
| Growth stage | < 6 months | Scaled, efficient acquisition |
| Enterprise SaaS | < 24 months | Long sales cycles tolerated |
LTV:CAC ratio
The LTV:CAC ratio compares lifetime value to acquisition cost: - < 1: You're paying more than a customer is worth. Not sustainable. - 1–3: Marginal. Revenue covers CAC but leaves little profit. - 3–5: Healthy. Strong unit economics. - > 5: Excellent. May signal you're under-investing in growth.
How to reduce CAC
Channel optimization: Measure CAC per channel (paid search, content, outbound, referral). Kill or reduce spend on channels with > 18-month payback. Double down on < 6-month channels.
Conversion rate: Higher website-to-trial conversion means more customers from the same ad spend. A/B testing landing pages is often the fastest CAC lever.
Sales efficiency: Measure deals closed per sales rep per month. Underperforming reps inflate blended CAC significantly.
Referral programs: Customer-referred acquisition typically has 2–3× lower CAC than paid channels. Invest in referral mechanics early.
Frequently asked questions
What does this calculator do? Calculate blended CAC from ad spend, sales payroll, and tools, plus CAC payback period using ARPU and gross margin.