NPS - Net Promoter Score: Definition & Calculation

Two firms report the same Net Promoter Score. At the first, half the customers are delighted and the other half are furious. At the second, almost nobody has a complaint and almost nobody is impressed either. One number, two companies with nothing in common.

The Net Promoter Score is a recommendation metric. You ask on a scale from 0 to 10 how likely a recommendation is, sort the answers into three groups and subtract the percentage of detractors from the percentage of promoters. The result lands somewhere between minus 100 and plus 100. By the end of this article you will have worked out an NPS yourself, know how to place it and spot the moments when it promises more than it can deliver.

📌 Key points at a glance

• The NPS measures willingness to recommend on a scale from 0 to 10.
• Promoters answer 9 or 10, detractors answer 0 to 6.
• NPS equals per cent promoters minus per cent detractors, passives do not count.
• The score always sits between minus 100 and plus 100.
• Fred Reichheld introduced the NPS in the Harvard Business Review in 2003.

What is the Net Promoter Score?

The Net Promoter Score is a customer loyalty metric that grows out of a single question: how likely is it that you would recommend us to a friend or a colleague? Answers run on a scale from 0 to 10.

Credit for the metric goes to the American loyalty researcher Fred Reichheld, who set it out in the Harvard Business Review in December 2003 under the title “The One Number You Need to Grow”. His argument was blunt: of all the questions you could put to a customer, one says more about future growth than any other, and that is the question about recommending you. Recommending a company means staking your own reputation on it, which is precisely why a recommendation counts for more than a tick in a box marked “satisfied”.

One detail most guides skip over is the legal one. “Net Promoter” and “NPS” are registered trademarks of Bain & Company, Inc., NICE Systems, Inc. and Fred Reichheld. Applying the method is free and publishing your own score is fine, but commercial use of the marks requires a licence and an attribution under Bain’s own terms on trademarks and licensing (as at September 2026). For a survey in a club, a course or your own shop that makes no difference at all. For an annual report it does.

Satisfaction measurement is a different exercise. Satisfaction looks backwards and asks how good an experience was. Willingness to recommend looks forwards and asks about an action someone has yet to take. The two can sit a long way apart, because plenty of people are content enough to stay put and still not convinced enough to bring anyone else along.

Promoters, passives and detractors: the three groups

The eleven answer options of the NPS collapse into three groups: promoters with 9 and 10, passives with 7 and 8, detractors with anything from 0 to 6. That split is the real heart of the method and it is lopsided, which throws most people on first contact.

Seven of the eleven possible answers therefore count as criticism. Reichheld justifies the cut with behaviour rather than symmetry: in his data, people who gave a 9 or a 10 behaved measurably differently from everybody else. They bought again more often and they brought new customers with them. The line falls where the behaviour changes, not in the middle of the scale.

A 0 to 10 scale is a rating scale with eleven steps. Laid out on screen it looks like a ruler with even gaps, and it is nothing of the sort: nobody can show that the step from 6 to 7 means the same as the step from 9 to 10. Which is exactly why the NPS counts shares instead of taking an average.

How to calculate the NPS: formula and worked example

The NPS is calculated by subtracting the percentage of detractors from the percentage of promoters. Passives drop out of the sum entirely and only count towards the total number of answers. Report the result as a whole number, without a per cent sign.

1. Sort the answers into three groups. Count how many answers fall on 9 to 10, on 7 to 8 and on 0 to 6.
2. Work out the shares in per cent. Divide each group by the total number of answers and multiply by 100.
3. Subtract detractors from promoters. What remains is your Net Promoter Score. From the three group figures you can calculate the NPS straight away.

A worked example with 200 completed questionnaires from a customer survey makes the arithmetic concrete.

From 48 per cent promoters minus 25 per cent detractors you get an NPS of plus 23. The 54 passive answers change nothing directly, they only press the figure down indirectly by swelling the total and shrinking both shares. Had the same 96 promoters and 50 detractors come from only 150 answers, the NPS would be plus 31.

💡 Tip

Report the three percentage shares and the number of answers alongside the NPS every time. Plus 23 from 200 answers and plus 23 from 12 answers look identical on a slide and are nothing like each other.

What counts as a good NPS?

No universal threshold for a good NPS exists. Only two statements are safe: from plus 1 upwards you have more promoters than detractors, and below zero the criticism wins. Everything else depends on sector, country and how you collected the answers, which is exactly why measuring yourself against other people’s figures is the commonest mistake of all.

The dependable reference point is your own time series. Measure the NPS over several quarters with the same question, the same moment in the customer journey and the same audience, and the movement tells you something real. Bain & Company sells sector benchmarks under the name NPS Prism, and that market exists because a bare score means so little without context. For an outside view, Britain offers something better than a scattering of self-reported scores: the UK Customer Satisfaction Index (UKCSI) has been published twice a year by the Institute of Customer Service since 2008, always on a consistent set of measures.

Response behaviour also varies between countries, which international surveys underrate with some regularity. Van Herk, Poortinga and Verhallen (2004) reported in the Journal of Cross-Cultural Psychology that the tendency to agree and the pull towards extreme scores were stronger in the Mediterranean countries studied than in north-western Europe. The United Kingdom was one of the six countries in that study and sat in the north-western group. A British score and a Spanish or Italian score from the same company are therefore not directly comparable.

⚠️ Careful

Do not hold your score up against published scores from other companies. Other people’s numbers come from different samples, different moments and often different languages. Compare your own score with your own last score, and keep the method constant while you do it.

Asking the NPS question properly in a questionnaire

The NPS question only works when wording, scale and timing line up. Reword the question, shorten the scale or ask at some arbitrary point, and you are measuring something else, at which point the comparison with your own last reading falls apart.

Placement matters as much as wording. Put the question at the very end of the questionnaire or let it stand on its own. Ask it after ten detailed questions about delivery times and packaging and your respondents will answer with those details in mind rather than the whole picture. How you put a questionnaire together helps decide what score comes out the other end.

Checklist for the NPS question

• The wording stays identical across every wave.
• The scale runs from 0 to 10, with nothing trimmed off.
• Both ends carry a label, such as “very unlikely” and “very likely”.
• An open follow-up question asking why sits directly underneath.
• The moment in the customer journey is the same every time.
• The question is voluntary, never a required field.

The open follow-up question is the most valuable part of the whole survey. The number tells you something is off, the open question tells you what. Reichheld built it into the method from the start, and in practice it is still the first thing to get cut.

For staff the same logic runs under the name eNPS, asking how likely people are to recommend their own employer. The sum is identical, you can calculate the eNPS in just the same way, the reading is trickier, because the groups are small and anonymity is hard to guarantee in a team of thirty. Measuring employee satisfaction properly therefore hangs on the procedure far more than on the metric.

What the NPS cannot do

The NPS is a deliberate simplification and every simplification carries a price. Anyone putting the score into a presentation should know three limits, because they explain how two identical scores can describe completely different situations.

None of these limits makes the NPS worthless. They mark where its remit ends. As an early warning system the metric earns its keep, as the sole basis for a decision it does not.

The NPS throws information away

Eleven gradations become three groups and three groups become one number. A company with 50 per cent promoters and 50 per cent detractors scores zero. A company with 20 per cent promoters, 60 per cent passives and 20 per cent detractors also scores zero. The first describes a split customer base with loud voices on both sides, the second a uniformly lukewarm one. Same number, two entirely different jobs to do.

Small samples make the NPS jump

The NPS is a difference between two shares, so it swings harder than an average taken from the same sample. At 50 answers a single response is worth 2 percentage points. If one person shifts from detractor to promoter, the score moves 4 points without anything at all having changed about the company. Report a 5 point improvement off 40 answers and you are reporting noise. How big a sample needs to be is no side issue here.

The link between NPS and growth is disputed

Reichheld’s central claim was that the NPS predicts growth better than rival loyalty measures. Keiningham, Cooil, Andreassen and Aksoy tested that in 2007 in the Journal of Marketing, using data from 21 companies and more than 15,500 interviews in the Norwegian Customer Satisfaction Barometer. Their finding: the claimed clear superiority of the NPS over other measures could not be confirmed in the very sectors Reichheld had held up as showcases. The paper won the 2007 H. Paul Root Award from the Marketing Science Institute.

The NPS is a thermometer, not a diagnosis. It tells you something is hot or cold, never why.

Common mistakes in NPS surveys

Most unusable NPS results come from the circumstances of the survey rather than from a slip in the arithmetic. Three patterns turn up again and again, and all three cost nothing to avoid.

Common to all three is that they push the score upwards. That is what makes them treacherous: an inflated NPS gets queried by nobody, because it is the pleasant news.

The NPS question arrives at the wrong moment

Straight after a complaint has been put right, people answer with relief and a generous hand. Three weeks later they answer far more soberly. Both readings are correct on their own terms, and together they build a time series that says nothing about the company and everything about when you chose to ask. Fix the moment once and hold to it, even when another moment looks more flattering.

The NPS becomes a target instead of a measurement

Once a bonus hangs on the NPS, people start asking for points. “If you were happy, please give us a 10, anything lower counts as a fail for us” is a sentence that destroys the metric. Reichheld named the problem himself in the Harvard Business Review in 2021 under the title “Net Promoter 3.0” and proposed a counterweight from the accounts, the Earned Growth Rate. That measure tracks how much revenue growth genuinely comes from returning customers and the people they refer.

Only part of the customer base gets asked

Sending the survey to your newsletter list means asking the people who already pay attention. Writing only to active accounts means asking the people who have not left yet. Both routes lift the score without anyone rigging a thing. Whether your result holds for your whole customer base is decided by who ends up in the survey, and the article on representativeness in online surveys sets out what that takes.

Conclusion

The Net Promoter Score is one of the few metrics that everyone in the team grasps immediately, and that is its greatest strength. Treat it as an early warning system and a way into a conversation, never as proof. What matters is not the score itself but what sits in the open answers underneath it, and whether the figure moves across several waves measured the same way. A lone NPS with no shares, no sample size and no point of comparison says almost nothing.

Where to go next

• Want to work out more metrics from your survey? Calculate metrics
• Planning the survey that goes with it? Customer surveys: guide and examples
• Answers already in? Evaluating a questionnaire in five steps
• Wondering why an average is the wrong tool here? Ordinal scale explained simply

Our reading tip: Anyone who wants the original argument first hand will find it in Reichheld’s 2003 essay in the Harvard Business Review. The counter position sits in the 2007 study by Keiningham and colleagues in the Journal of Marketing. Read together, the two give a more honest picture than any summary.

Want to measure the NPS in a survey of your own?

empirio.ai, an online survey tool from Germany, has NPS as its own question type and the analysis works the score out for you. See the customer feedback templates