What is Net Promoter Score (NPS)?

Net Promoter Score (NPS) is a widely used measure of customer loyalty based on a single question: 'How likely are you to recommend us to a friend or colleague?' answered on a 0-to-10 scale. From those answers you get one number that summarizes how customers feel.

NPS is popular because it's simple, quick, and comparable across companies and over time. It captures something powerful: whether customers like you enough to put their own reputation behind a recommendation.

How NPS is calculated

Respondents are sorted into three groups by their score, and the calculation is just the difference between your fans and your critics. The result ranges from -100 to +100.

• Promoters (9–10): loyal fans likely to recommend you.
• Passives (7–8): satisfied but unenthusiastic, and easily lured away.
• Detractors (0–6): unhappy customers who may warn others off.
• NPS = % promoters − % detractors.

Why NPS matters for validation

A high NPS suggests customers love the product enough to spread it by word of mouth — a powerful, cheap growth engine and a sign of product-market fit. During validation, asking early users this question reveals whether you've built something merely tolerable or genuinely loved. Enthusiastic promoters early on are a strong signal you're onto something worth scaling.