Per-subscriber variable costs include cloud hosting, payment processing fees (2-3%), customer support time, and third-party API usage. SaaS businesses typically enjoy low variable costs, which is why they can scale profitably once past break-even.

Churn means you need to continuously acquire new subscribers just to maintain your current count. High churn raises the effective break-even point because a portion of new sales simply replaces lost customers rather than adding net revenue.

Monthly analysis is most common since SaaS metrics revolve around MRR (Monthly Recurring Revenue). Use monthly fixed costs and monthly subscription prices for consistency. Annual figures can be useful for strategic planning but may mask month-to-month cash flow issues.