Net Promoter Score (NPS) measures customer loyalty through a simple question: "How likely are you to recommend [brand] to a friend?" Respondents rate 0-10, then are categorized as Promoters (9-10), Passives (7-8), or Detractors (0-6). NPS = % Promoters - % Detractors.
NPS scores range from -100 (all detractors) to +100 (all promoters). Scores above 0 are generally positive, above 50 are excellent, and above 70 are world-class. Comparing NPS to industry benchmarks contextualizes performance.
Beyond the score itself, following up to understand why customers gave their rating provides actionable insights. Detractors reveal problems to fix, while understanding what creates promoters helps replicate success.