What is Net Promoter Score?
NPS rests on a single question with a scale from 0 to 10. Answers of 9 to 10 count as promoters, 7 to 8 as passives, 0 to 6 as detractors. The score is the percentage of promoters minus the percentage of detractors - which is why the scale runs from -100 to +100, and why passives drop out of the calculation entirely.
The metric was popularised in 2003 by Fred Reichheld in the Harvard Business Review under the title "The One Number You Need to Grow". That very claim is the point of contention: marketing research has disputed the assertion that NPS predicts growth better than established satisfaction indices. The score measures sentiment, not revenue.
In practice the conditions matter more than the score. Who is asked (all customers or only the happy ones), when they are asked (right after purchase or after six months of use) and how many responded shift the result more than any genuine improvement. An NPS without sample size and collection date is a claim, not a metric.
Why does Net Promoter Score matter?
NPS is a calculation rule, not a law of nature - a score of +40 cannot be interpreted without industry, sample and timing. It becomes useful as your own time series: same question, same audience, same moment in the customer relationship, several quarters in a row. As proof in a reference, the collection framework always belongs beside it.
Net Promoter Score in practice
- 01With 100 responses split into 50 promoters, 30 passives and 20 detractors, the NPS is +30.
- 02Surveying only customers whose support ticket ended well lifts the score - and makes it worthless.
- 03The open follow-up question about the reason is always worth adding; the free-text answers are the real return on the survey.
