Customer Acquisition Cost Calculator
Customer acquisition cost is total go-to-market spend divided by customers acquired in the same period. The blended figure is the right denominator for unit economics; the paid-only figure is the right one for marketing spend efficiency.
The two CAC numbers
Investors and operators use blended CAC for unit economics — pairing it with LTV to test viability. They use paid CAC to evaluate marketing efficiency, because including organic customers in the denominator hides the cost of incremental growth: turning off paid spend would save the spend but also stop the paid customers from arriving, while the organic customers would mostly still come.
What belongs in the numerator
Include everything that exists to acquire customers: paid media, marketing salaries, sales salaries and commissions, agency retainers, content production, conferences, sales tools (CRM, prospecting, calling), and a fair allocation of marketing-ops headcount. Exclude post-sale costs (customer success, onboarding, support) — those belong in the cost of revenue or in your retention math.
What belongs in the denominator
New paying customers in the period — not trials, not signups, not MQLs. If your sales cycle is long, lag the denominator: customers closed in Q3 from spending in Q1 should attribute to Q1's CAC. For B2B with multi-quarter cycles, compute trailing-twelve-month CAC against trailing-twelve-month new logos.
Worked example
A B2B SaaS company spent $180,000 on marketing and $420,000 on sales (fully loaded) last quarter and acquired 150 new customers, 40 of which came through partner referrals. Blended CAC: $4,000. Paid CAC: $5,455. The blended figure is what they pair with their $24,000 average LTV (LTV/CAC of 6×, healthy). The paid figure is what they use to evaluate whether to scale paid acquisition further.
What CAC doesn't account for
- Channel mix. A $4,000 blended CAC could mask a $20,000 CAC on one channel and a $1,000 CAC on another. Compute by channel before scaling spend.
- Time lag. Pairing this quarter's spend with this quarter's new customers overstates efficiency in a slowing business and understates it in an accelerating one.
- Cohort variation. First customers in a market are cheap; saturation makes incremental customers expensive. Average CAC and marginal CAC diverge as you scale.
- Overhead allocation. Cleanly separating GTM headcount from product or G&A is a judgment call; pick a method and apply it consistently.