What is NPS and how to measure it: Net Promoter Score guide

How do you know whether your customers truly love you, before they leave? The most common and simplest way to measure customer loyalty is NPS, based on a single question. But NPS is often misused: either it's seen as just a number that turns into no action, or the real value behind it (the customer's "why") is ignored.

This guide explains what NPS is, how it's calculated, what a good score is, and how to actually turn it into action. We covered building loyalty itself in our customer loyalty program article.

What is NPS (Net Promoter Score)?

NPS is a customer loyalty metric that measures how likely your customers are to recommend your brand to others. It's based on a single question: "How likely are you to recommend us to a friend or colleague?" The customer rates this from 0 to 10. This simplicity makes NPS one of the most widely used customer loyalty measures in the world; a single number summarizes how your whole customer base feels about you.

How is NPS calculated?

Customers are split into three groups by their score:

• Promoters (9-10): Loyal, enthusiastic customers; they actively recommend you.
• Passives (7-8): Satisfied but not enthusiastic; they may switch to a competitor.
• Detractors (0-6): Unhappy customers; they can spread a negative experience.

The formula is simple: NPS = percentage of Promoters − percentage of Detractors. Passives aren't counted. The result is a number between -100 and +100. For example, 60% promoters and 20% detractors means an NPS of 40.

Detractorsscore 0–6Passives7–8Promoters9–10NPS = %Promoters − %Detractors

What is a good NPS score?

Because NPS ranges from -100 to +100, a positive score (above zero) is generally a good sign; because your promoters outnumber your detractors. As a rough guide: above 0 is acceptable, above 30 good, above 50 excellent, above 70 world-class. But a "good" score varies greatly by industry; the most meaningful comparison is with your own past score and your industry average. More than the absolute number, the score rising over time is what matters.

Why does NPS matter?

NPS isn't just a satisfaction measure but an indicator of the future. A high NPS is associated with higher loyalty, lower churn and stronger organic growth (through referrals). Promoters buy more, stay longer and market you for free; detractors both leave and spread their negative experience. So tracking NPS lets you see your customer base's health and growth potential early.

How and when to ask the NPS survey?

You can measure NPS in two ways: to all customers at regular intervals (relational NPS) or right after a specific interaction (transactional NPS). Keep the survey short — ideally one question plus an open follow-up. The right timing is critical: NPS asked right after a purchase, a support conversation or a milestone gives the freshest and most accurate answer. Deliver the survey on the channel most suitable for your customer, such as email, SMS or in-app.

The real value: the open "why?" question

The most often-neglected but most valuable part of NPS is the single question asked after the score: "What's the main reason for your score?" The number itself tells you "what"; the open answer tells you "why." That's where the real insight is: from these answers you learn why detractors are unhappy, what promoters love, and what would make passives enthusiastic. Adding up the number without reading the comments is the biggest NPS mistake.

Turning NPS into action: the closed loop

An NPS that's measured but not acted on is just a number. The real value is in the "closed loop" approach: acting after feedback comes in. Reach detractors and solve their problems — this both saves that customer and gives you the most valuable improvement ideas. Find small steps that would make passives enthusiastic. From promoters, ask for a referral, reference or review; they're your biggest growth source.

NPS's limits and common mistakes

• Looking only at the number: Tracking the score without reading the comments misses the real value.
• Not acting: Measuring and doing nothing creates survey fatigue and distrust.
• Gaming the score: Steering customers toward a high score makes the metric meaningless.
• Blindly trusting a single metric: NPS is valuable but incomplete alone; it should be read alongside other measures.

NPS vs CSAT vs CES

NPS isn't the only customer experience metric; each measures something different. NPS measures overall loyalty and willingness to recommend (the long-term relationship). CSAT (Customer Satisfaction) measures immediate satisfaction with a specific interaction ("How satisfied are you with this experience?"). CES (Customer Effort Score) measures how easy it was to get something done. The healthiest approach is using these metrics together as complementary pieces.

How do you improve NPS?

The only way to raise NPS is to act on the feedback behind it. Find detractors' common complaints and solve the root cause — often a few recurring issues drag down most of the score. Learn what promoters love and reinforce it. After making improvements, measure again and track the change. Improving NPS is less about running surveys and more about genuinely improving the customer experience.

Relational and transactional NPS

Two types emerge depending on when you ask NPS. Relational NPS is asked at regular intervals (e.g. quarterly), independent of any specific interaction, and measures the health of the customer's overall relationship with the brand. Transactional NPS is asked right after a specific touchpoint (a purchase, a support conversation) and measures the impact of that interaction. The two complement each other: relational NPS shows the big picture, transactional NPS shows which moments push the score up or down.

Sample size and reliability

For NPS to be meaningful, you need enough responses. A score calculated from too few responses is overly swayed by a handful of extreme opinions and doesn't reflect the real picture. Try to reach as broad and representative an audience as possible; but also avoid overwhelming customers with constant surveys. Interpreting the score by its trend over time rather than a single measurement prevents small fluctuations from misleading you.

Employee NPS (eNPS): starting from the inside

The same logic applies to your employees. eNPS (Employee NPS) measures how likely your employees are to recommend the company as a place to work. This matters because happy, engaged employees often deliver a better customer experience; customer loyalty is usually a reflection of employee satisfaction. If you want to improve your customer NPS, starting from the inside — your team's experience — is often a powerful step.

NPS and customer feedback with Rocketly

Rocketly lets you send NPS surveys automatically at the right moments, log responses to the customer record, and see detractor/passive/promoter groups at a glance. You set up an automatic follow-up flow for detractors and ask promoters for referrals — that is, you close the loop. By keeping every piece of feedback with the customer's history in your CRM, you turn NPS from a number into real improvements and growth opportunities.