What the Net Promoter Score is
The Net Promoter Score (NPS), introduced by Fred Reichheld of Bain & Company in 2003, measures customer loyalty with a single question:
How likely is it that you would recommend us to a friend or colleague?
Customers answer on a scale from 0 to 10 and fall into three groups:
| Score | Group |
|---|---|
| 9 to 10 | Promoters: loyal enthusiasts |
| 7 to 8 | Passives: satisfied but unenthusiastic |
| 0 to 6 | Detractors: unhappy customers |
The formula
NPS = % promoters − % detractors
The result ranges from −100, if everyone is a detractor, to +100, if everyone is a promoter. Passives count in the total but not in the subtraction.
Worked example
Out of 100 responses, 60 are promoters, 25 passives and 15 detractors:
| Result | Value |
|---|---|
| Net Promoter Score | 45 |
| Margin of error (95%) | ±14.5 points |
| Promoters | 60% |
| Passives | 25% |
| Detractors | 15% |
The margin of error
Because NPS is a difference between two proportions, it is noisy on small samples. The calculator uses the standard formula:
margin = 1.96 × √((p + d − (p − d)²) ÷ n)
where p and d are the shares of promoters and detractors and n the number of responses. With 100 responses, a change of 10 points between two surveys may be pure chance; you need several hundred responses to detect small changes reliably.
What is a good NPS?
| NPS | Common reading |
|---|---|
| Below 0 | More detractors than promoters |
| 0 to 29 | Room for improvement |
| 30 to 49 | Good |
| 50 to 69 | Excellent |
| 70 or more | Exceptional |
Benchmarks differ widely between industries and countries, so compare yourself with your sector and with your own past scores.
Tips
- Always ask a follow-up open question, such as “What is the main reason for your score?”: the comments are often more useful than the number.
- Survey at consistent moments, for example after delivery or support, to compare like with like.
- Close the loop with detractors quickly; it is often the fastest way to raise the score.