Calculating NPS: Formula, Examples, and Common Errors

To calculate Net Promoter Score (NPS), subtract the percentage of detractors from the percentage of promoters among people who answered a 0–10 recommendation question. Enter the number of responses in each group to get an NPS from −100 to +100, along with the group percentages.

Formula

NPS = percentage of promoters − percentage of detractors. In count form, the same formula is:

NPS = 100 × (P − D) / R

• P is the number of promoters, people who gave a score of 9 or 10.
• D is the number of detractors, people who gave a score from 0 through 6.
• R is the total number of valid responses: promoters + passives + detractors.

Passives are respondents who score 7 or 8. They count in the total response denominator, but they are not added to either side of the promoter-minus-detractor calculation. NPS is expressed as a score in points, not as a percentage, even though its calculation uses percentages.

Worked Example

Using the calculator’s default values, there are 60 promoters, 25 passives, and 15 detractors. The total is 60 + 25 + 15 = 100 responses.

1. Promoter percentage: 100 × 60 / 100 = 60.0%.
2. Passive percentage: 100 × 25 / 100 = 25.0%.
3. Detractor percentage: 100 × 15 / 100 = 15.0%.
4. NPS: 60.0 − 15.0 = 45 points.

The equivalent count calculation is 100 × (60 − 15) / 100 = 45. The result is 45, not 45%.

How to Classify Responses

NPS generally begins with one recommendation question asking respondents to rate how likely they are to recommend a company, product, service, or experience to someone else. The commonly used response scale runs from 0, “not at all likely,” to 10, “extremely likely.” Scores are grouped as follows:

• Detractors: 0–6. These are the lower scores in the NPS grouping.
• Passives: 7–8. These middle scores are included in the total but not counted as promoters or detractors.
• Promoters: 9–10. These are the highest scores in the grouping.

Use the same question wording, scale, and grouping rules across the results you intend to compare. If a survey uses a different scale or assigns categories differently, its score is not directly comparable to a standard NPS calculation unless the method is made consistent.

What the Score Means

The possible range is −100 to +100. A score of +100 means every valid respondent was a promoter; −100 means every respondent was a detractor. A score of zero means the promoter share and detractor share are equal. Passives can make up some or most of the responses even when the score is zero.

A positive NPS means promoters outnumber detractors as a share of responses; it does not mean that every respondent is satisfied, or that a particular percentage would recommend the organization. For example, an NPS of 45 does not mean 45% of respondents are promoters. In the worked example, 60% are promoters and 15% are detractors, giving an NPS of 45 points.

There is no universal benchmark that makes a score “good” in every context. Results vary with the industry, audience, country, survey method, timing, and question wording. Trends within a consistently measured group can be informative, but comparisons across organizations require care.

Response Counts, Rounding, and Common Errors

Calculate percentages from the valid responses included in the result—not from the number of people invited unless everyone responded. If a person skipped the recommendation question, decide whether that response is excluded and apply that rule consistently. The calculator assumes the three category counts include all valid answers and that their total is greater than zero.

• Do not subtract raw counts unless the groups are equally sized in the intended denominator. The standard formula compares percentages, or equivalently divides the difference in counts by the total response count.
• Do not omit passives from the denominator. They are not part of the numerator difference, but they are valid responses.
• Keep full precision until the final result. Rounding each group percentage too early can shift the reported score slightly.
• Report the response count and method. A score alone does not reveal how many people answered or how the sample was gathered.
• Do not treat a small change as automatically meaningful. Response counts, sampling variation, and changes in who answered all affect interpretation.

For example, if 18 people are promoters, 12 are passives, and 10 are detractors, the total is 40. NPS = 100 × (18 − 10) / 40 = 20 points. It is not 8 points (the raw count difference) and not 45 points (the promoter percentage alone).

Using NPS Responsibly

NPS compresses responses into one number, which makes it easy to summarize and track. That simplicity also hides information: a score does not show the distribution across all 11 answer options, the reasons behind a rating, or whether the respondent’s experience was recent or representative.

It is useful to review the underlying response distribution and, where appropriate, follow up with an open-ended question about the reason for the score. Keep survey timing and audience selection in mind. A change in the mix of respondents can move NPS even if the experience of a particular customer group has not changed.

When comparing periods or groups, use consistent definitions and disclose the number of responses. NPS describes the answers collected; by itself, it does not prove what caused a change or establish that respondents will actually recommend or stop using something.

Frequently Asked Questions

Can NPS be negative?
Yes. NPS is negative when the detractor percentage exceeds the promoter percentage. Its lowest possible value is −100.

Do passives count in NPS?
Yes, passives count in the total number of responses used to calculate the percentages. They are not included in the promoter-minus-detractor difference.

Is NPS a percentage?
No. It is reported as a score in points from −100 to +100. Its formula uses promoter and detractor percentages, but the final difference is not itself a percentage of promoters.

How many responses do I need to calculate NPS?
One or more valid responses are enough to perform the arithmetic, provided the total is not zero. A larger response count does not by itself guarantee a representative result; how respondents were selected and who answered also matters.

How do I calculate NPS in a spreadsheet?
If cells contain promoter, passive, and detractor counts, calculate 100*(promoters-detractors)/(promoters+passives+detractors). Format or round the result as a score, and ensure the denominator is not zero.

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in p | Promoters (9–10) | people | 60 | 0
in n | Passives (7–8) | people | 25 | 0
in d | Detractors (0–6) | people | 15 | 0
out nps | Net Promoter Score | points | 100 * (p - d) / (p + n + d) | 0
out promoters | Promoters | % | 100 * p / (p + n + d) | 1
out passives | Passives | % | 100 * n / (p + n + d) | 1
out detractors | Detractors | % | 100 * d / (p + n + d) | 1