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Glossary

What Is Customer Acquisition Cost (CAC)?

The total cost to acquire one paying customer, including marketing, sales, and overhead.

Definition

Customer Acquisition Cost (CAC) is the total cost to acquire one new paying customer, including all marketing spend, sales costs, content production, and supporting overhead. The basic formula is: CAC = Total Acquisition Spend ÷ New Customers Acquired in the same period.

CAC is one half of the unit economics equation — paired with LTV, it determines whether your subscription business is profitable to grow. Most subscription businesses track several CAC variants: blended CAC (all customers), paid CAC (only customers from paid channels), and channel-specific CAC.

Why It Matters for WooCommerce Stores

CAC determines how much you can spend to grow. If CAC is $150 and LTV is $800, you have a healthy 5.3:1 ratio with $650 lifetime profit per customer — strong economics for aggressive growth.

If CAC is $400 and LTV is $400, you break even with no margin for error. CAC trends matter as much as the absolute number: rising CAC over time signals channel saturation, increased competition, or product-market fit erosion.

For WooCommerce subscription stores, declining or stable CAC with growing customer count is the strongest signal of sustainable growth.

How It Works

Calculate total acquisition cost by summing: marketing spend (ads, content, SEO tools), sales costs (commissions, sales tooling, sales salaries), partial overhead (marketing team salaries, dev resources for marketing), and divide by new customers acquired. The tricky part is allocation: should CEO time spent on marketing count?

Most businesses use a "fully loaded" CAC that includes proportional overhead. Track CAC monthly to spot trends.

For multi-touch attribution, use UTMs to assign customers to source channels for channel-specific CAC.

Real-World Example

A WooCommerce subscription store spent $5,000 last month: $3,500 on Facebook ads, $1,000 on content writers, $500 on SEO tools. They acquired 100 new paying subscribers.

Blended CAC = $5,000 ÷ 100 = $50. Looking by channel: Facebook drove 60 customers at $3,500 = $58 CAC; content/SEO drove 40 customers at $1,500 = $37 CAC.

If their LTV is $400, both channels are profitable (LTV:CAC of 6.9:1 and 10.8:1), but content has better unit economics.

Best Practices

  • Track blended CAC and paid CAC separately — they tell different stories
  • Calculate channel-specific CAC to know where to scale and where to cut
  • Include "fully loaded" costs (salaries, tools, overhead) not just ad spend
  • Measure CAC payback period — months until LTV exceeds CAC — should be under 12 months
  • Watch CAC trends month-over-month — rising CAC is an early warning of channel saturation

Common Mistakes

  • Only counting direct ad spend, ignoring marketing salaries and tooling
  • Not segmenting by channel — blended CAC hides which channels are unprofitable
  • Including organic/word-of-mouth customers in paid CAC denominator (deflates the number artificially)
  • Setting CAC targets without LTV context — $200 CAC is good for $1,000 LTV, bad for $250 LTV
  • Ignoring CAC payback period — even great LTV:CAC ratios strain cash flow with long payback

In WooCommerce with WPSubscription

WPSubscription tracks subscription order data including UTM parameters from the originating signup, letting you calculate channel-specific CAC by comparing subscription source to marketing spend. Combine with Google Analytics 4 conversion tracking for a complete acquisition picture.

See how WPSubscription handles this →

Related How-to Guides

How to Track Subscription Revenue in WooCommerce

Monitor MRR, churn, and subscription health using WPSubscription and WooCommerce reports.

Frequently Asked Questions

What costs should I include in CAC?
Include all marketing spend (ads, content, tools), sales costs (commissions, sales staff), and a proportional share of marketing overhead (team salaries, dev resources for marketing pages). Exclude product development, customer support, and general operations — those are retention costs.
How is CAC different from CPA (Cost Per Acquisition)?
CPA usually refers to a single channel's cost per conversion (e.g., Facebook ads CPA). CAC is the holistic cost across all channels and overhead. For decision-making at the subscription business level, CAC matters more; for ad campaign optimization, channel-specific CPA matters more.
What's a healthy CAC payback period?
Under 12 months is healthy for SaaS-style subscription businesses. 6 months or less is excellent. Over 18 months strains cash flow — you're financing customer acquisition with future revenue. Subscription businesses with long payback periods often need external capital to grow.
How do referrals affect CAC calculations?
Referral incentives (discounts, credits) are an acquisition cost and should be included in CAC for referred customers. However, referrals typically have lower CAC than paid channels — sometimes 30-50% lower — which is why referral programs are often the highest-ROI marketing investment.
Should I cut channels with high CAC?
Not necessarily — high CAC channels can be profitable if they bring high-LTV customers. Compare LTV:CAC ratio by channel, not raw CAC. A $200 CAC channel that delivers $1,500 LTV customers (7.5:1) is far better than a $50 CAC channel delivering $200 LTV customers (4:1).

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