CAC (Customer Acquisition Cost) is the total marketing + sales spend to acquire one new customer. Different from CPA: CAC includes all spend (team salaries, tools, agency fees), CPA is only ad spend. The core sustainability metric for SaaS, subscription and high-LTV models.
formula
CAC = (Total Marketing + Sales Spend) / New Customers Acquired
"Total spend" matters. Loaded CAC includes: ad budget, marketing salaries, sales salaries + commission, CRM/tooling subs, agency fees, content production, events, etc. Just dividing ad spend by customers gives you "paid CAC"; real CAC is usually 1.5-3x higher.
LTV:CAC ratio
CAC alone is meaningless; read with LTV:
- LTV:CAC < 1 · losing money on each customer.
- LTV:CAC ≈ 1-2 · break-even, hard to grow.
- LTV:CAC ≈ 3 · healthy SaaS standard.
- LTV:CAC > 5 · under-investing in growth.
CAC payback period
CAC payback = CAC / Monthly Gross Margin. How many months until a customer pays back acquisition cost.
- SaaS healthy threshold: <12 months.
- One-time-purchase e-commerce: payback at first order.
- Subscription / membership: 6-9 months preferred.
lowering CAC
- Organic channels · SEO, content, referral cut CAC 30-60% but require 6-12 months investment.
- Funnel optimization · landing CR 2% → 4% halves CAC.
- Channel mix · shift from expensive to cheap; MMM grounds this in data.
- Self-serve onboarding · for SaaS, removing demo-call requirement zeros out sales-team CAC.
Example: A B2B SaaS reported $1,400 paid CAC. Loaded CAC (including sales + marketing salaries + tools) was $3,950. LTV $9,300 → LTV:CAC = 2.4 (borderline). After 9 months of self-serve trial flow + product-led growth, CAC dropped to $2,400, ratio jumped to 3.9; investor-ready.