Fully-Loaded vs. Partial CAC
Many companies undercount CAC by excluding salaries, benefits, and overhead. A fully-loaded CAC includes every dollar spent on sales and marketing: team salaries and benefits, commissions and bonuses, software tools, ad spend, content creation, events, and allocated overhead. Partial CAC (ad spend only) can be 3-5× lower than fully-loaded, giving a dangerously optimistic view of unit economics.
The Magic Number
The SaaS Magic Number (popularized by Scale VP) measures how efficiently sales and marketing spend converts to recurring revenue. Calculate it as: Net New ARR this quarter divided by total S&M spend last quarter. Above 0.75 means each dollar of S&M generates $0.75+ of new ARR — a signal to invest more aggressively. Below 0.50 signals that the go-to-market motion needs fundamental optimization before scaling.