Net Promoter Score (NPS) Calculator
Calculate Net Promoter Score from counts, percentages or raw 0-10 scores. Get its margin of error, compare two NPS results for significance and plan improvements.
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How to calculate NPS
Net Promoter Score comes from one question: "How likely are you to recommend [brand] to a friend or colleague?" on a 0 to 10 scale.
- Promoters answer 9 or 10.
- Passives answer 7 or 8.
- Detractors answer 0 to 6.
NPS = % promoters − % detractors. It ranges from −100 (everyone a detractor) to +100 (everyone a promoter). Passives count in the base but not in the score.
How to use the NPS calculator
- Enter your counts of promoters, passives and detractors, or the percentages and base, or paste the raw 0–10 scores.
- Read the score, its margin of error and its likely range.
- To check whether NPS really moved, enter the previous wave or a competitor's figures in the comparison fields.
- Enter a target to see how many customers you would need to move to reach it.
Why NPS needs a margin of error
NPS is the difference of two percentages, so its sampling error is larger than either percentage on its own. With 500 respondents and a typical split, NPS carries a margin of about ±7 points at 95% confidence. A drop from 22 to 18 between quarters is very likely noise. Many dashboards report these swings as news; the calculator stops that.
Worked example
A quarterly survey of 750 customers has 312 promoters, 254 passives and 184 detractors.
- Promoters 41.6%, detractors 24.5%, so NPS = +17.1
- Variance = 0.416 + 0.245 − 0.171² = 0.632; SE = √(0.632 ÷ 750) = 2.9 points
- 95% range: +11.4 to +22.8
Last quarter's NPS was +8 (36% promoters, 28% detractors, 690 respondents). The 9-point rise is significant (p ≈ 0.03). Press Example to load it.
Comparing NPS across countries
NPS norms differ by culture. Respondents in some markets rarely give 9 or 10 to anyone, while others score generously. A German NPS of +10 and a Brazilian NPS of +40 may reflect the same real loyalty. When you benchmark across countries, compare each market with its own history or with local competitors, not with a global average.
Frequently asked questions
What is a good NPS?
Anything above 0 means more promoters than detractors. Scores vary widely by industry and country, so the most useful benchmark is your own trend and your direct competitors measured the same way.
How many responses do I need for NPS?
For a margin of about ±10 points you need roughly 250–400 responses, depending on the split. For ±5 points, around 1,000–1,500.
Is NPS a percentage?
No. It is a score from −100 to +100, written without a % sign.
Can I average NPS across segments?
Only weighted by each segment's size. Better still, pool the promoters, passives and detractors and recalculate.
Need the respondents, not just the numbers?
Global Vox Populi runs quantitative and qualitative fieldwork in 170+ countries through its own proprietary panels of consumers, B2B and IT decision-makers, physicians, nurses, patients, caregivers and payers. ISO 9001, ISO 20252 and ISO/IEC 27001 certified and HIPAA compliant, following ESOMAR and Insights Association guidelines.
Check feasibilityLink to this tool
Free to use in proposals, courses and articles. If it helped, a link back is appreciated:
<a href="https://globalvoxpopuli.com/tools/nps-calculator/">NPS Calculator</a> by Global Vox Populi