Net Promoter Score Formula
Understand the NPS formula, how promoters/passives/detractors are counted, rounding rules, examples, and common calculation mistakes.
Short answer: NPS is calculated as % promoters minus % detractors.
Net Promoter Score formula
The Net Promoter Score formula subtracts the percentage of detractors from the percentage of promoters.
Passives are included in the total number of responses, but they do not directly add to or subtract from the score.
What counts as promoters, passives, and detractors
| Response score | NPS group | Used directly in formula? |
|---|---|---|
| 9-10 | Promoters | Yes, as % promoters |
| 7-8 | Passives | No, but included in total responses |
| 0-6 | Detractors | Yes, as % detractors |
Step-by-step formula
- Count all responses.
- Count promoters: scores of 9 and 10.
- Count passives: scores of 7 and 8.
- Count detractors: scores of 0 through 6.
- Divide promoters by total responses and multiply by 100.
- Divide detractors by total responses and multiply by 100.
- Subtract detractor percentage from promoter percentage.
Worked NPS formula example
Imagine you have 100 responses: 55 promoters, 25 passives, and 20 detractors.
Promoters make up 55% of responses and detractors make up 20%. The NPS is 55 minus 20, which gives a score of 35.
| Category | Responses | Share |
|---|---|---|
| Promoters | 55 | 55% |
| Passives | 25 | 25% |
| Detractors | 20 | 20% |
Example with passives
Passives do not appear in the final subtraction, but they still matter because they increase the total response count.
If two companies have the same number of promoters and detractors but different numbers of passives, their percentages and final NPS can differ.
| Scenario | Promoters | Passives | Detractors | NPS |
|---|---|---|---|---|
| A | 50 | 0 | 50 | 0 |
| B | 50 | 50 | 50 | 0 |
| C | 50 | 100 | 25 | 17 |
Rounding NPS
NPS is normally reported as a whole number, not as a percentage sign. If the calculation produces decimals, round consistently and document the rule in reports.
For example, if promoters are 48.6% and detractors are 21.4%, the NPS is 27.2. Many reports would show this as 27.
Common NPS formula mistakes
- Subtracting detractor count from promoter count instead of using percentages.
- Forgetting that passives count in total responses.
- Adding a percent sign to the final NPS score.
- Mixing response scales or changing the NPS question mid-trend.
- Comparing NPS results without checking sample size and survey timing.
Related pages on Calculator for NPS
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Frequently Asked Questions
Why are passives excluded from the formula?
Passives are neutral. They are counted in total responses, but they do not directly influence the score.
What is the highest possible NPS?
The highest possible NPS is +100, which happens when every respondent is a promoter.
Is NPS a percentage?
NPS is calculated from percentages, but the final score is usually reported as a number from -100 to +100, not with a percent sign.
Do passives affect NPS?
Yes, indirectly. Passives are included in total responses, so they affect the promoter and detractor percentages even though they are not subtracted directly.