CAC

CAC is calculated as total marketing and sales spend over a period divided by new customers in that same period. The math is easy; the scope of the numerator is where most disagreements happen. Counting only ad spend turns CAC into something close to CPA. A fully-loaded CAC adds salaries, content, tooling and referral payouts — and that fully-loaded version is what investors expect to see in any pitch deck.

CAC sits at the centre of unit economics for startups and SaaS. CAC payback under 12 months is generally read as healthy; over 24 months and you are looking at a capital efficiency problem. Public SaaS benchmark reports put mid-market payback in the 15-18 month range, with Korean SaaS often running slightly longer due to market size and procurement cycles. Even the famous LTV:CAC = 3:1 rule of thumb is really an indirect way of asking the same payback question.

Strong teams almost always split CAC by channel and by segment rather than reading the blended number. A blended CAC of $100 hides the fact that paid search costs $200, content and SEO drive customers at $65, and referral lands them at $25. The same applies to SMB versus enterprise — averaged together, your real sales efficiency disappears. Decomposing CAC is the starting line for marketing mix optimisation, not an afterthought.

AI search and recommendation are quietly breaking CAC attribution. A user who hears about you inside a ChatGPT answer and types your name into Google three days later is recorded as organic or direct in GA4. The real cost of that customer is whatever you spent on the GEO work that landed in the AI answer — and that line item lives nowhere on a standard P&L. Korean teams are responding the same way US ones are: leaning more on media mix modelling, incrementality testing and surveying customers about their first-touch channel.

The most durable lever for lowering CAC is, unsurprisingly, channel diversification and a higher share of organic acquisition. Paid-only companies watch CAC creep up as auction competition tightens. Toss leaned on a viral hook (free transfers) early to dilute paid dependency. Globally, Notion and Linear used content and community to keep CAC flat as they scaled. The dependable progression is paid → content → SEO → GEO → referral → community, layering organic assets one at a time so the CAC curve stays flat through the growth.