Definition
Payback measures how long cash is tied up in each new customer. It is the most practical efficiency metric for a growing company because it connects marketing spend directly to runway.
Formula
CAC paybackCAC payback (months) = S&M expense ÷ (New MRR × Gross margin %)
Example
A company spends $310,000 on sales and marketing in a quarter and adds $27,600 of new MRR at a 78% gross margin. Payback = 310,000 ÷ (27,600 × 0.78) = 14.4 months.
Benchmarks
Under 12 months is excellent, 12 to 18 is healthy for most B2B SaaS, and enterprise products can justify longer. The trend matters as much as the level.
Common mistakes
- Using revenue instead of gross profit.
- Ignoring a slow drift because each quarter looks close to the last.
- Mismatched periods, such as this quarter’s spend against last quarter’s customers.
Examples use Demo Co, a fictional $3M ARR SaaS company, or a generic company where noted. Benchmarks are common reference points, not targets for every business.