NPS Calculator: Calculate Net Promoter Score (Free)

How to calculate NPS

Collect 0–10 answers: Ask “How likely are you to recommend us to a friend or colleague?” on a 0–10 scale.
Group the respondents: Count promoters (9–10), passives (7–8) and detractors (0–6), or enter how many people chose each score.
Subtract: NPS = % promoters − % detractors. The calculator does it instantly and shows the breakdown.
Check the margin of error: Read the 95% confidence interval to see how precise your score is before comparing it over time.

Person analyzing survey charts on a laptop next to a phone and glasses

The Net Promoter Score formula

NPS = % promoters − % detractors

Promoters (9–10): enthusiastic customers who are likely to recommend you.
Passives (7–8): satisfied but unenthusiastic. They count in the total but don’t change the score directly.
Detractors (0–6): unhappy customers who may discourage others.

Worked example

Say 200 customers answer your NPS survey: 120 give a 9 or 10, 50 give a 7 or 8, and 30 give 0–6. Promoters are 120 ÷ 200 = 60% and detractors are 30 ÷ 200 = 15%, so NPS = 60 − 15 = +45. With 200 responses, the 95% margin of error is about ±10.3 points, so the true score is likely between roughly +35 and +55.

Why the margin of error matters

NPS is a difference between two proportions, so it is noisier than a simple percentage. With small samples, a change of 5–10 points from one month to the next can be pure chance. Before you report a trend, check whether the confidence intervals overlap. To plan how many responses you need, use the survey sample size calculator.

NPS vs. CSAT

NPS measures loyalty and likelihood to recommend, usually as a periodic relationship metric. Customer satisfaction (CSAT) measures satisfaction with a specific interaction, such as a purchase or support ticket, typically on a 1–5 scale. Many teams use both: CSAT right after an interaction and NPS every quarter. See our customer satisfaction survey template.

Run your NPS survey with Florm

Florm has a built-in NPS question that groups respondents automatically and shows your score in form analytics, next to completion rate and drop-off. Start from the NPS survey template or read how Florm calculates NPS.

NPS calculator FAQ

What is a Net Promoter Score?

Net Promoter Score (NPS) is a customer loyalty metric based on one question: “How likely are you to recommend us to a friend or colleague?” answered on a 0–10 scale. It is the percentage of promoters (9–10) minus the percentage of detractors (0–6).

What is the NPS formula?

NPS = (promoters ÷ total responses × 100) − (detractors ÷ total responses × 100). Passives (7–8) count toward the total but are not added or subtracted.

What is the range of NPS?

NPS ranges from −100 (every respondent is a detractor) to +100 (every respondent is a promoter). It is usually reported as a whole number without a percent sign.

Is NPS a percentage?

No. Although it is calculated from two percentages, NPS is reported as a score between −100 and +100, not as a percentage.

How is the NPS margin of error calculated?

This calculator uses the standard variance for a difference of proportions: variance = (p + d) − (p − d)², where p and d are the shares of promoters and detractors. The 95% margin of error is 1.96 × √(variance ÷ n), expressed in NPS points.

How many responses do I need for a reliable NPS?

It depends on how precise you need the score to be. The margin of error shrinks with the square root of the sample size, so halving it requires about four times as many responses. Use the margin of error shown above, or our sample size calculator, to plan.

Does this NPS calculator store my data?

No. All calculations run in your browser. Nothing you enter is sent to Florm or stored.