Net Promoter Score calculator
Calculate your NPS from counts or paste raw 0–10 survey answers, see the margin of error so you know how much the score can move by chance, and check whether a change from last quarter is real. Free, no sign-up, nothing leaves your browser.
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The method
How to calculate Net Promoter Score
One question, three groups, one subtraction.
NPS comes from one question: "How likely are you to recommend us to a friend or colleague?", answered on a scale from 0 to 10. Bain & Company, which created the method, groups answers into promoters (9–10), passives (7–8) and detractors (0–6). The score is the share of promoters minus the share of detractors, so it runs from −100 to +100. Passives count in the total but not in the subtraction.
60% and 15%
120 ÷ 200 = 60% · 30 ÷ 200 = 15%
200 answers: 120 promoters, 50 passives, 30 detractors.
NPS +45
60 − 15 = 45
Passives (25%) lower the shares, not the formula.
±10 points
95% interval: 34 to 55
The true score could be anywhere in this range.
Statistics
NPS margin of error
With a few hundred answers, NPS moves by several points by chance alone.
The calculator uses the adjusted-Wald method that Jeff Sauro and Jim Lewis of MeasuringU recommend for NPS: add three quarters of a response to promoters and to detractors and one and a half to passives, then compute the interval from the variance of the score. The adjustment keeps intervals honest for small samples.
| Answers | Typical 95% margin of error |
|---|---|
| 50 | about ±20 points |
| 200 | about ±10 points |
| 800 | about ±5 points |
The table assumes a variance like the example above; your own result shows the exact margin and how many answers you would need for ±5 or ±10 points.
Compare
Did our NPS really change?
A score that went from 30 to 37 may still be noise.
The Compare two tab works out the difference between two scores and its confidence interval. If the interval does not include zero, the change is unlikely to be chance at the confidence level you picked. If it does include zero, collect more answers before you celebrate or worry.
Compare like with like: the same question, the same kind of customers and the same moment in the customer journey. A survey sent right after a support chat and one sent at renewal measure different things.
Practice
Running an NPS survey that you can trust
The number is only as good as the way you ask.
One question, then why
Ask the 0–10 question first, then one open question such as "What is the main reason for your score?". The reasons tell you what to fix.
Everyone, not the happy few
Send the survey to a full group of customers, not only to those who just praised you. Low response rates from unhappy customers make the score look better than it is.
Close the loop
Reply to detractors within days, fix what they raise and tell them what changed. Track the score over time instead of comparing with other companies' numbers collected in other ways.
Spreadsheets
NPS formulas for Excel and Google Sheets
Answers 0–10 in A2:A201.
Net Promoter Score from raw answers
Share of promoters
Share of detractors
FAQ
Net Promoter Score questions
How do you calculate NPS?
Ask "How likely are you to recommend us to a friend or colleague?" on a 0–10 scale. Take the percentage of 9s and 10s (promoters) and subtract the percentage of 0–6 answers (detractors).
Is NPS a percentage?
No. It is the difference between two percentages, written as a number from −100 to +100, for example +45, not 45%.
Why don't passives count?
They do count in the total number of answers, which lowers the shares of promoters and detractors. They are left out of the subtraction because they are neither loyal nor unhappy enough to move the score.
What is a good NPS?
Any score above zero means more promoters than detractors. Published benchmarks differ by industry, country and survey method, so the most useful comparison is with your own previous scores collected the same way.
How many responses do I need for NPS?
For a margin of error of about ±10 points at 95% confidence you typically need around 200 answers; for ±5 points, around 800. The calculator shows the number for your own data.
How do I know if my NPS change is significant?
Use the Compare two tab. If the confidence interval of the difference does not include zero, the change is unlikely to be random at the confidence level you chose.
Does the calculator store my answers?
No. Everything runs in your browser. The share link keeps your numbers in the address after the # sign, which is not sent to our server; pasted answers are not included in the link.
References
Sources
- Question, groups and calculation: Bain & Company, "Measuring Your Net Promoter Score", checked October 6, 2026
- Adjusted-Wald confidence intervals for NPS: Jim Lewis and Jeff Sauro, "Sample Sizes for Comparing Net Promoter Scores", MeasuringU, June 22, 2021
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