What is Churn rate?

Two churn rates, two meanings

Customer churn = customers lost ÷ customers at the start of the period.

Revenue churn = recurring revenue lost ÷ recurring revenue at the start.

They diverge, and the direction of the divergence is diagnostic. Revenue churn far above customer churn means your larger accounts are the ones leaving. Revenue churn below customer churn means you are losing small accounts while the big ones stay — a much better position, and invisible if you only track the headcount.

Net revenue churn subtracts expansion from existing customers. When expansion exceeds losses it goes negative, and revenue grows from the existing base alone. That is the structural advantage behind most durable subscription businesses.

The growth ceiling

If you add 100 customers a month and churn 5% monthly, growth stops at 2,000 customers — the point where 5% of the base equals the 100 you can add. Halving churn to 2.5% doubles the ceiling to 4,000, with no change to acquisition at all.

This is why churn work often beats acquisition work on the same budget: acquisition buys a linear increase, churn reduction moves the asymptote.

Measuring it honestly

• Fix the denominator. Customers at the start of the period, not an average across it, and not the end-of-period count.
• Beware small numbers. With 40 customers, one cancellation is 2.5% and the monthly figure is mostly noise. Use a longer window or a cohort view.
• Separate voluntary from involuntary. Failed payments are a billing problem with a technical fix, not a product problem. Blending them hides an easy win.
• Split by acquisition channel. Channels differ enormously in the quality of customer they send, and a blended churn rate averages your best source with your worst.