[elsewhen]

You are not screwing it up as much as you think. A zero rating has the same impact as a 6 on NPS.

0-6 counts as a-1

7-8 counts as a 0

9-10 counts as a +1

NPS is an average of these numbers so if every user gave a seven or eight, the NPS would be zero (which is a mediocre but not terrible NPS score)

https://cdn.business2community.com/wp-content/uploads/2016/0...

[bornabox]

It's actually the percentage of (+1) minus the percentage of (-1). 7-8's are literally not being counted (as you said 0's). Imagine if 990/1000 give 7 or 8. Out of the remaining 10, 7 give a 9 and 3 any number below 6. The count would be: 70%-30%=40 (which would be a good outcome). But only 1% of everyone that participated ended up determining the actual NPS Score.

[kelnos]

I don't think that's right, and the example given in the article seems to agree with me. The 7s&8s are indeed counted, indirectly: the score is the percent of all responses (including 7s&8s) that are promoters minus the percent of detractors.

So, using your example, 990/1000=99% of people are passive, 7/1000=0.7% are promoters, and 3/1000=0.3% are detractors, so the NPS score is 0.7-0.3, or 0.4 (not 40). Passives aren't a part of the last calculation, but they affect the percent values for promoters and detractors.