The ideal Customer Acquisition Cost (CAC) to Lifetime Value (LTV) ratio is 1:3 or better — meaning each customer should generate at least 3x what you paid to acquire them. Most profitable ecommerce brands target LTV:CAC of 4:1 to 5:1. An LTV:CAC below 2:1 signals unsustainable growth. For subscription or D2C brands, a customer with $100 CAC should generate at least $400 in lifetime revenue to be considered healthy.