顧客獲得コスト（CAC）

Customer acquisition cost (CAC) divides acquisition-related sales and marketing spend by the number of new customers acquired in the same period. It is not just ad spend. Depending on the operating definition, it can include sales headcount, commissions, agency fees, events, tools, and creative production. CAC is useful only when paired with LTV, gross margin, payback period, and channel mix.

The basic formula divides acquisition spend by new customers. Operators usually separate blended CAC, channel CAC, and CAC payback so budget decisions are not made from one average. Basic formula | CAC = acquisition spend / new customers | Measures average acquisition cost Channel CAC | channel spend / new customers from that channel | Compares paid, referral, outbound, and partner efficiency CAC payback | CAC / monthly gross profit per customer | Shows how many months it takes to recover acquisition spend

CAC changes dramatically depending on which costs and customers are included. Fix the cost pool, time window, and customer-counting rule before comparing teams or periods. Include | Ad spend, sales and marketing payroll, commissions, agencies, events, acquisition tools, creative costs | They support new customer acquisition Exclude | Existing-customer support, product development, renewal management, dedicated upsell costs | They belong to retention or expansion economics Define carefully | Brand spend, founder-led sales, free trials, referral rewards, long sales cycles | Attribution and timing can be ambiguous

CAC moves with market competition, channel mix, conversion rate, sales productivity, pricing, and target segment. Media cost | CPC or CPM rises | Paid acquisition becomes more expensive Conversion rate | Lead-to-customer rate changes | Same spend produces more or fewer customers Sales cycle | Deals take longer | Headcount cost and payback period rise Segment | SMB, mid-market, and enterprise differ | CAC and LTV need separate benchmarks

Guides which channels and segments deserve more growth budget. Shows whether customer acquisition should be scaled, paused, or redesigned when compared with LTV. Connects growth speed to cash planning through CAC payback.

• Guides which channels and segments deserve more growth budget.
• Shows whether customer acquisition should be scaled, paused, or redesigned when compared with LTV.
• Connects growth speed to cash planning through CAC payback.

• CAC should include the acquisition costs required to win customers, not only ads.
• Blended CAC hides which channels are efficient or fragile.
• CAC needs LTV, gross margin, and payback context.
• Enterprise and SMB motions can justify very different CAC levels.
• Optimizing only for low CAC can attract poor-fit customers and raise churn.

CAC is not a metric to minimize blindly. High-LTV customers can justify higher acquisition cost if payback and retention are healthy. Short measurement windows can penalize channels with longer sales cycles. CAC excluding sales payroll or commissions is usually too optimistic for investment decisions. Improving CAC is not enough if LTV, NRR, or churn is deteriorating.

• Short measurement windows can penalize channels with longer sales cycles.
• CAC excluding sales payroll or commissions is usually too optimistic for investment decisions.
• Improving CAC is not enough if LTV, NRR, or churn is deteriorating.

Read CAC with LTV, payback period, ARR, churn, and NRR to understand the quality of growth investment. LTV | Future customer value | Sets the ceiling for acceptable acquisition cost CAC payback | Months to recover cost | Connects growth to cash pressure Churn Rate | Customer or revenue loss | High churn makes CAC harder to recover ARR / MRR | Recurring revenue growth | Shows whether acquisition spend becomes durable revenue

A SaaS company spends $120k on ads, $150k on sales payroll, and $30k on events and tools in a quarter, acquiring 250 customers. Blended CAC is $1,200. Channel analysis shows referrals at $600 CAC and outbound at $2,400 CAC, but outbound customers have higher LTV and pay back within 12 months. The team scales referrals while keeping outbound focused on high-LTV segments instead of blindly shifting all spend to the lowest CAC source.

CAC | Cost to acquire one new customer | Measures growth efficiency CPA | Cost per action or lead | Measures pre-customer marketing efficiency ROAS | Revenue per ad dollar | Focuses on advertising performance CAC payback | Time to recover CAC through gross profit | Measures cash burden LTV/CAC | Customer value versus acquisition cost | Tests unit economics

• CAC is just ad spend. For operating decisions, sales payroll, commissions, tools, and acquisition programs usually matter.
• Lower CAC is always better. Cheap but poor-fit customers can churn quickly and weaken the business.
• Company-wide average CAC is enough. Segment and channel CAC often reveal the real growth motion.