Total sales and marketing spend divided by all new customers, including organic and word-of-mouth; a true all-in cost that can flatter or hide paid-channel performance.
Blended CAC divides total sales and marketing spend by all new customers acquired in a period, including those who came through organic or word-of-mouth channels at near-zero marginal cost. KPI Tree describes it exactly this way, and contrasts it with paid CAC that isolates paid channels (kpitree.co). Wall Street Prep makes the same distinction between blended CAC (all customers) and new or paid CAC (paid only) (wallstreetprep.com).
Blended CAC is the honest all-in figure for what it costs the business, on average, to add a customer. Its weakness is that strong organic can mask weak paid: if half your customers arrive free, blended CAC looks healthy even when paid acquisition is underwater. That is why it should never be read alone.
Worked example (Demonstrative): A$120,000 total sales and marketing spend acquiring 600 new customers (400 paid, 200 organic) gives a blended CAC of A$200. But the new-customer (paid) CAC is A$120,000 / 400 = A$300, because the spend bought only the paid customers. The blended figure understates the real cost of the paid engine by a third.
Blufire keeps the full CAC suite (blended, new-customer, marginal) side by side and computes LTV against contribution margin, so blended CAC is read as context, not as the number you bid against.