List churn measures subscriber attrition — unsubscribes, hard bounces, and spam complaints — relative to list size. Healthy creator newsletters see 0.5–2% monthly churn. High churn (3%+) signals content-audience mismatch, over-mailing, or list quality problems. Net list growth = new subscribers minus churn. Creators focused on sustainable growth monitor churn alongside acquisition and re-engage inactive subscribers before they unsubscribe.