Net Promoter Score Formula: Classifying Customer Loyalty Into Actionable Segments
Net Promoter Score (NPS) is a customer loyalty metric based on a single survey question: "How likely are you to recommend [product/company] to a friend or colleague?" Respondents answer on a 0-10 scale and are classified into three groups: Promoters (9-10) are enthusiastic advocates who drive referrals and revenue growth, Passives (7-8) are satisfied but unenthusiastic customers vulnerable to competitive offers, and Detractors (0-6) are unhappy customers who may damage brand reputation through negative word-of-mouth.
The NPS formula subtracts the percentage of detractors from the percentage of promoters: $$\text{NPS} = \%\text{Promoters} - \%\text{Detractors}$$ The score ranges from -100 (all detractors) to +100 (all promoters). Passives are excluded from the calculation but still matter strategically as a convertible segment. For example, if 200 respondents include 100 promoters (50%), 60 passives (30%), and 40 detractors (20%), the NPS is 50\% - 20\% = +30.
NPS was developed by Fred Reichheld and Bain & Company and published in the Harvard Business Review in 2003. Its adoption has become near-universal across industries because the single-question format produces high response rates (10-30% vs 2-5% for longer surveys), the score is easy to communicate to leadership, and longitudinal tracking reveals customer loyalty trends that correlate with revenue growth and churn patterns.
Integrating open-ended follow-up questions ("What is the primary reason for your score?") captures Qualitative feedback that provides immediate context to quantitative NPS scores, accelerating root-cause resolution for customer satisfaction teams.
Evaluating overall NPS shifts across sequential quarterly cohorts provides clear visibility into long-term customer sentiment trajectory.