Net Promoter Score: worked example
| Promoters (9 to 10) | 140 |
|---|---|
| Passives (7 to 8) | 90 |
| Detractors (0 to 6) | 70 |
| Net promoter score | 23.3 |
| Promoters share | 46.7% |
| Detractors share | 23.3% |
Net Promoter Score: formula
Common error: Reading the score as a percentage. It is a difference of two percentages, so +23 does not mean 23 percent of customers are happy.
The standard recommendation question uses a 0-to-10 scale: promoters answer 9 or 10, passives 7 or 8, and detractors 0 through 6. Passives count in the total but not in the score. Use a consistent survey method and a large enough sample; a few dozen responses give a noisy number.
Survey at a consistent point in the customer journey.
Net Promoter Score: changing Promoters (9 to 10)
| Promoters (9 to 10) | Net promoter score | Promoters share | Detractors share |
|---|---|---|---|
| 112 | 15.4 | 41.2% | 25.7% |
| 126 | 19.6 | 44.1% | 24.5% |
| 140 (example) | 23.3 | 46.7% | 23.3% |
| 154 | 26.8 | 49.0% | 22.3% |
| 168 | 29.9 | 51.2% | 21.3% |
Net Promoter Score: compare input ranges
| Input | Tested from | To | Net promoter score: low input | Net promoter score: high input | Swing |
|---|---|---|---|---|---|
| Promoters (9 to 10) | 126 | 154 | 19.6 | 26.8 | 7.2 (31%) |
| Detractors (0 to 6) | 63 | 77 | 26.3 | 20.5 | 5.8 (25%) |
| Passives (7 to 8) | 81 | 99 | 24.1 | 22.7 | 1.4 (6.0%) |
Net Promoter Score: individual input comparisons
| Input | Value | Net promoter score | Promoters share | Detractors share |
|---|---|---|---|---|
| Promoters (9 to 10) | 112 | 15.4 | 41.2% | 25.7% |
| 126 | 19.6 | 44.1% | 24.5% | |
| 140 | 23.3 | 46.7% | 23.3% | |
| 154 | 26.8 | 49.0% | 22.3% | |
| 168 | 29.9 | 51.2% | 21.3% | |
| Passives (7 to 8) | 72 | 24.8 | 49.6% | 24.8% |
| 81 | 24.1 | 48.1% | 24.1% | |
| 90 | 23.3 | 46.7% | 23.3% | |
| 99 | 22.7 | 45.3% | 22.7% | |
| 108 | 22 | 44.0% | 22.0% | |
| Detractors (0 to 6) | 56 | 29.4 | 49.0% | 19.6% |
| 63 | 26.3 | 47.8% | 21.5% | |
| 70 | 23.3 | 46.7% | 23.3% | |
| 77 | 20.5 | 45.6% | 25.1% | |
| 84 | 17.8 | 44.6% | 26.8% |
Net Promoter Score: combined input changes
| Promoters (9 to 10) / Passives (7 to 8) | 72 | 90 | 108 |
|---|---|---|---|
| 112 | 16.5 | 15.4 | 14.5 |
| 126 | 20.9 | 19.6 | 18.4 |
| 140 | 24.8 | 23.3 | 22 |
| 154 | 28.4 | 26.8 | 25.3 |
| 168 | 31.6 | 29.9 | 28.3 |
Net Promoter Score: which assumptions move the result?
Net Promoter Score: values and definitions
| Quantity and definition | Value used |
|---|---|
| Promoters (9 to 10) | 140 |
| Passives (7 to 8) | 90 |
| Detractors (0 to 6) | 70 |
| Net promoter score | 23.3 |
| Promoters share | 46.7% |
| Detractors share | 23.3% |
Net Promoter Score: half and double Promoters (9 to 10)
| Promoters (9 to 10) | Net promoter score |
|---|---|
| 70 | 0 |
| 140 | 23.3 |
| 280 | 47.7 |
NPS reflects sentiment and does not itself predict growth, and small samples and response bias, where unhappy or delighted customers answer most, distort it. Cultural differences in scoring make comparisons across countries misleading. Combining passives and detractors hides differences.
Act on the detractors first.
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The net promoter score is the share of promoters minus the share of detractors, and passives drop out of the sum. With 140 promoters, 90 passives and 70 detractors, promoters are 46.7 percent and detractors 23.3 percent, so the score is +23. It runs from -100 to +100, and a positive score only means promoters outnumber detractors.
Look at the size of the sample. A score built from a few dozen replies can swing many points from a few different answers.
Connect satisfaction to money with customer lifetime value and churn calculators, and see the conversion rate page for the funnel. The A/B test significance calculator helps judge whether a change in score is real. Follow up with detractors directly.
Do the 90 passives affect the example score?
Yes. They are included in all 300 responses, so 140/300 minus 70/300 gives 23.33 points. Removing them would change the denominator and overstate the score.
What is a good Net Promoter Score?
Zero means promoters and detractors have equal shares. A score of 30 or 50 is a larger positive difference, not a universal good-or-excellent rating. Compare a relevant sample, question and collection method before using any outside benchmark; survey selection can change who the number represents.
How large should the sample be?
Sample size alone does not establish stability. Selection matters. A few hundred responses can still misrepresent customers if the invitation or response pattern is biased; examine the promoter and detractor counts, response method and period, and use an appropriate uncertainty calculation before interpreting a small score change.
What should I do with the score?
Track it over time, read the comments, and follow up with detractors. Use it to find causes of dissatisfaction, not as a target to game.