Customer acquisition cost (CAC) is the total cost to acquire one new customer. The basic formula is: total sales and marketing spend divided by the number of new customers gained in the same period. If you spend $20,000 on SEO, PPC, landing pages, creative, software, and sales support in a month and win 40 new customers, your CAC is $500.
How to calculate CAC accurately
For search-led growth teams, CAC should include the full cost of acquiring demand, not just ad spend. That usually means PPC media spend, SEO retainers or in-house salaries, content production, landing page design, CRO tools, call tracking, reporting software, and the sales labor tied to closing those leads.
Use a consistent time window and match spend to actual customer outcomes. If your sales cycle is 45 days, do not compare this month’s spend to this month’s closed customers without adjusting for lag. That creates misleading CAC numbers and can make profitable campaigns look inefficient.
Simple CAC formula
CAC = total acquisition cost / new customers acquired
Why CAC matters in SEO and PPC
CAC tells you whether your growth engine is economically sustainable. In paid search, it helps you decide how aggressively to bid, which campaigns to scale, and when a keyword is too expensive to justify. In SEO, it helps quantify whether organic investment is producing lower-cost customer acquisition over time compared with paid channels.
It also becomes more useful when paired with conversion rate, lead quality, and customer lifetime value. A keyword with a high cost per click may still be profitable if it drives high-intent traffic that converts into valuable accounts. On the other hand, a low-cost traffic source can destroy efficiency if the landing page attracts unqualified leads.
Practical example for a search campaign
An agency spends $12,000 in one month on Google Ads management, media spend, landing page testing, and call tracking for a B2B software campaign. The campaign generates 60 qualified leads, and 12 become customers. The CAC is $1,000.
If the average first-year gross profit per customer is $4,000, that CAC may be strong. If profit is only $700, the campaign is upside down. The next move is not just “lower spend.” It is to improve keyword targeting, tighten match types, cut wasteful queries, and increase landing page conversion rate so more of the same traffic becomes revenue.
How to improve CAC without choking growth
Start with search intent. Prioritize keywords closer to purchase, split branded and non-branded campaigns, and build landing pages that match the exact query. Measure calls, forms, pipeline, and closed revenue, not just clicks and leads. For SEO, focus on pages that can rank for commercial terms with clear conversion paths. For PPC, push budget toward campaigns with proven close rates, not just cheap conversions. The goal is lower CAC through better targeting and better conversion economics, not simply less spend.