Why it matters to a buyer
SEO's CAC calculation is different from paid channels in a way that is easy to misrepresent: the cost is the ongoing investment in content, technical work and links rather than a per-click spend, and it tends to fall over time as content compounds, unlike paid CAC, which stays roughly flat or rises as a channel's costs increase. A buyer comparing SEO to paid search on CAC alone should account for this different cost shape, and for SEO's longer payback period before results ramp up.
How it is measured or applied
CAC for organic search is calculated by dividing the total cost of SEO work, whether an agency retainer, in-house salaries, or content production, over a period by the number of new customers attributed to organic search in that same period, using whichever attribution model the business has chosen. It is compared against the same calculation for other channels, and against average customer lifetime value, to judge whether the channel's return justifies its cost. It is tracked over multiple quarters rather than month to month, since organic CAC is expected to improve gradually as content and authority accumulate.
Sources
- About the Cost per acquisition metric, Google Ads Help
