NPS Calculator (Net Promoter Score)
Net Promoter Score from the counts of promoters, passives and detractors, with each group's share and the margin of error of the score.
Results
Net Promoter Score
45.0
Share of promoters
60.0
%
Share of passives
25.0
%
Share of detractors
15.0
%
Margin of error (95 %), in points
14.5
What this tool does
NPS subtracts the share of detractors (scores 0 to 6) from the share of promoters (9 and 10); passives count in the total but in neither group, so the score runs from −100 to +100. What most dashboards leave out is the margin of error: with 100 answers a score of 45 can easily be anywhere from about 30 to 60, so a move of five points between two months usually means nothing. The margin here treats each answer as +1, 0 or −1 and uses the normal approximation.
Formula
NPS = % promoters − % detractors · margin ≈ 1.96 × √((p_P + p_D − (p_P − p_D)²) ÷ n) × 100
Variables
| Symbol | Meaning | Unit |
|---|---|---|
pr | Promoters (scores 9–10) | — |
pa | Passives (scores 7–8) | — |
de | Detractors (scores 0–6) | — |
NP | Net Promoter Score | — |
SP | Share of promoters | % |
SS | Share of passives | % |
SD | Share of detractors | % |
ME | Margin of error (95 %), in points | — |
Worked example
- Promoters (scores 9–10)60
- Passives (scores 7–8)25
- Detractors (scores 0–6)15
- Net Promoter Score45.0
- Share of promoters60.0 %
- Share of passives25.0 %
- Share of detractors15.0 %
- Margin of error (95 %), in points14.5
Limitations
- Standard deviation and variance are calculated for a sample (dividing by n − 1). For a full population, divide by n instead.
- The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.