The NPS formula
NPS = % of promoters − % of detractors.
Customers answer one question: 'How likely are you to recommend us to a friend, from 0 to 10?' Scores of 9–10 are promoters, 7–8 are passives, and 0–6 are detractors. Passives count in the total but not in the score.
The result ranges from −100 (everyone is a detractor) to +100 (everyone is a promoter). Example: 200 responses with 120 promoters (60%) and 30 detractors (15%) give an NPS of +45.
