People search for an NPS calculator when a survey comes back as a stack of scores from 0 to 10.
Net promoter score is the share of promoters minus the share of detractors. Reichheld’s 2003 HBR article, indexed on PubMed, uses one question. How likely are you to recommend this company, from 0 to 10?
Promoters are 9 and 10. Passives are 7 and 8. Detractors are 0 through 6.
The net promoter score calculator writes that as:
(promoters - detractors) / (promoters + passives + detractors) × 100
Passives stay in the denominator. They are answers. They pull the score toward zero.
The page rounds the score to a whole number. Shares round to one decimal. These examples use that formula. They are not a survey design, and they are not a forecast of growth.
Fig 1
One question, three buckets
Passives stay in the count
Subtract detractors from promoters, then divide by promoters, passives, and detractors together.
What the score is, and what it leaves out
Read the score first. Then read the three shares. A 45 from 60% promoters is a different room from a 45 that hides a large passive block.
Customers who left in a period are a different ratio. That is the customer churn calculator and the churn post. Revenue that stayed, expanded, or arrived is the MRR calculator and the MRR post. Lifetime value of the accounts you keep is the LTV:CAC calculator.
Reichheld’s method does not publish a cutoff on this page. The calculator does not grade 45 as good or bad. It returns the subtraction.
Example 1: the calculator defaults
Inputs: 60 promoters, 25 passives, 15 detractors.
Responses: 60 + 25 + 15 = 100
Promoters minus detractors: 60 - 15 = 45
Score: 45 / 100 × 100 = 45
Shares: promoters 60 / 100 = 60%. Passives 25 / 100 = 25%. Detractors 15 / 100 = 15%.
Calculator result
Net promoter score
- Promoters (scores 9–10)
- 60 responses
- Passives (scores 7–8)
- 25 responses
- Detractors (scores 0–6)
- 15 responses
45
net promoter score
- Promoter share
- 60%
- Detractor share
- 15%
- Passive share
- 25%
Of the 100 answers, 75 were not detractors. That 75% is a different number from the score. The score uses 60% minus 15%.
Fig 2 · 1/3
Where the 100 answers sit
Defaults. 60 promoters, 25 passives, 15 detractors.
Promoters
60
Passives
25
Detractors
15
60 answers are promoters. That is 60% of the survey.
25 passives and 15 detractors make up the rest. The score is 60 minus 15.
Example 2: leaving the passives out
Inputs: 50 promoters, 40 passives, 10 detractors. Still 100 answers.
Score: (50 - 10) / 100 × 100 = 40
Shares: promoters 50%, passives 40%, detractors 10%.
A common shortcut drops the passives and divides by promoters plus detractors only.
50 + 10 = 60
40 / 60 × 100 = 66.7
The formula’s result on these inputs is 40. The 66.7 uses a smaller denominator, so the same 40-person gap looks larger. The 40 passives answered 7 or 8. They belong in the count.
Fig 3 · 1/2
Same 100 answers, two denominators
50 promoters, 40 passives, 10 detractors.
Score
Full count
40
Passives out
66.7
With passives in the count the score is 40.
Dividing only by the 60 promoters and detractors produces 66.7.
Example 3: ten answers, then one more detractor
Inputs: 6 promoters, 2 passives, 2 detractors.
Responses: 10
Score: (6 - 2) / 10 × 100 = 40
Shares: promoters 60%, passives 20%, detractors 20%.
Move one more person into the detractor bucket. Inputs become 6, 2, and 3. Responses are 11.
(6 - 3) / 11 × 100 = 27.272…, which the page rounds to 27
Shares: promoters 6 / 11 = 54.5%. Detractors 3 / 11 = 27.3%. Passives 2 / 11 = 18.2%.
One extra detractor moved the displayed score from 40 to 27. On a survey of 10, that is the whole story of the week. I would treat it as a conversation with those 10 people.
Example 4: one week and the same mix over a year
Week inputs: 12 promoters, 5 passives, 8 detractors.
Responses: 12 + 5 + 8 = 25
Score: (12 - 8) / 25 × 100 = 16
Shares: promoters 12 / 25 = 48%. Detractors 8 / 25 = 32%. Passives 5 / 25 = 20%.
Scale that mix by 40. Year inputs: 480 promoters, 200 passives, 320 detractors.
Responses: 1,000
Score: (480 - 320) / 1,000 × 100 = 16
The score matches because the shares match. The year did not get “more NPS” by collecting more of the same answers.
Now move one person from detractor to promoter.
On the week, inputs become 13, 5, and 7. (13 - 7) / 25 × 100 = 24. The displayed score rises by 8.
On the year, inputs become 481, 200, and 319. (481 - 319) / 1,000 × 100 = 16.2, which the page rounds to 16. Promoter share is 48.1%. Detractor share is 31.9%.
Same one-person move. The week jumps. The year still prints 16.
Example 5: counting an 8 as a promoter
Ten scores: 10, 9, 9, 8, 8, 8, 7, 6, 4, 2.
Promoters are the 10 and the two 9s. That is 3.
Passives are the three 8s and the 7. That is 4.
Detractors are the 6, the 4, and the 2. That is 3.
Score: (3 - 3) / 10 × 100 = 0
Shares: promoters 30%, passives 40%, detractors 30%.
If the 8s are filed with the promoters, the buckets become 6 promoters, 1 passive, and 3 detractors.
(6 - 3) / 10 × 100 = 30
The scores did not change. The cutoff did. HBR’s grouping puts 8 with the passives, so this list scores 0.
Example 6: 800 answers
Inputs: 420 promoters, 310 passives, 70 detractors.
Responses: 420 + 310 + 70 = 800
(420 - 70) / 800 × 100 = 43.75, which the page rounds to 44
Shares: promoters 420 / 800 = 52.5%. Detractors 70 / 800 = 8.8% (8.75% to one decimal). Passives 310 / 800 = 38.8% (38.75% to one decimal).
Calculator result
Net promoter score
- Promoters (scores 9–10)
- 420 responses
- Passives (scores 7–8)
- 310 responses
- Detractors (scores 0–6)
- 70 responses
44
net promoter score
- Promoter share
- 52.5%
- Detractor share
- 8.8%
- Passive share
- 38.8%
43.75 is the exact ratio. The headline on the page is 44. If you track the score month to month, keep the unrounded ratio in a sheet and let the page do the display rounding when you want the same whole number.
Example 7: a negative score
Inputs: 18 promoters, 22 passives, 40 detractors.
Responses: 80
(18 - 40) / 80 × 100 = -27.5, which the page rounds to -28
Shares: promoters 18 / 80 = 22.5%. Detractors 40 / 80 = 50%. Passives 22 / 80 = 27.5%.
Calculator result
Net promoter score
- Promoters (scores 9–10)
- 18 responses
- Passives (scores 7–8)
- 22 responses
- Detractors (scores 0–6)
- 40 responses
-28
net promoter score
- Promoter share
- 22.5%
- Detractor share
- 50%
- Passive share
- 27.5%
A negative score means detractors outnumber promoters. Passives do not cancel that. They only sit in the 80.
Another mix with the same shape of problem: 8 promoters, 70 passives, 22 detractors.
(8 - 22) / 100 × 100 = -14
Shares: promoters 8%, passives 70%, detractors 22%. Most people were fine enough to score a 7 or an 8. The score is still negative because 22 detractors beat 8 promoters.
Example 8: the three ceilings
All promoters. Inputs: 40, 0, 0.
(40 - 0) / 40 × 100 = 100
Promoter share 100%. The other two shares are 0%.
All detractors. Inputs: 0, 0, 30.
(0 - 30) / 30 × 100 = -100
Detractor share 100%.
All passives. Inputs: 0, 10, 0.
(0 - 0) / 10 × 100 = 0
Passive share 100%. Nobody would strongly recommend the company, and nobody scored it 0 to 6. The score sits at zero because the two groups that enter the subtraction are empty.
One lone promoter is also a ceiling. Inputs: 1, 0, 0. The score is 100 on a single answer. The formula does that. A sample of one is that one person.
Zero answers are the other edge. Promoters, passives, and detractors all 0. The page stops and asks for survey responses, because the division has no denominator.
Example 9: a large passive block
Inputs: 90 promoters, 180 passives, 30 detractors.
Responses: 300
(90 - 30) / 300 × 100 = 20
Shares: promoters 90 / 300 = 30%. Passives 180 / 300 = 60%. Detractors 30 / 300 = 10%.
People sometimes subtract the detractor share from 100 and call that the score. 100 - 10 = 90. That 90 is the share who were not detractors. The score is 30% minus 10%, which is 20.
Fig 4 · 1/3
Three surveys, three mixes
Counts, not shares. The score still uses the shares.
Responses
- Promoters
- Passives
- Detractors
| Category | Promoters | Passives | Detractors |
|---|---|---|---|
| 100 answers | 60 | 25 | 15 |
| 300 answers | 90 | 180 | 30 |
| 800 answers | 420 | 310 | 70 |
The default survey has 60 promoters out of 100.
The 300-answer book is mostly passives, so the score is 20. The 800-answer book rounds to 44.
Example 10: a cleaner 50
Inputs: 200 promoters, 50 passives, 50 detractors.
Responses: 300
(200 - 50) / 300 × 100 = 50
Shares: promoters 200 / 300 = 66.7%. Passives and detractors are each 50 / 300 = 16.7%.
Put this next to Example 1. Both can be described as “a positive score.” One is 45 with a 25% passive share. One is 50 with a 16.7% passive share. The subtraction is the headline. The shares tell you which bucket to read next.
Fig 5 · 1/5
Scores from the same formula
Whole numbers, the way the page rounds them.
NPS
- NPS
| Category | NPS |
|---|---|
| Defaults | 45 |
| 10 answers | 40 |
| Week of 25 | 16 |
| 800 answers | 44 |
| 300 passive | 20 |
The default 100 answers score 45. Ten answers with the same promoter share score 40.
A week of 25 scores 16. Eight hundred answers round to 44. A passive-heavy 300 scores 20.
The ten results side by side
| Example | Promoters | Passives | Detractors | Responses | Score | Notes |
|---|---|---|---|---|---|---|
| 1. Defaults | 60 | 25 | 15 | 100 | 45 | Shares 60%, 25%, 15% |
| 2. Passives kept | 50 | 40 | 10 | 100 | 40 | Dropping passives prints 66.7 |
| 3. Ten answers | 6 | 2 | 2 | 10 | 40 | One more detractor rounds to 27 |
| 4. Week | 12 | 5 | 8 | 25 | 16 | One move lifts it to 24 |
| 4. Same mix, year | 480 | 200 | 320 | 1,000 | 16 | One move still prints 16 |
| 5. Eights as passives | 3 | 4 | 3 | 10 | 0 | Filing 8s as promoters prints 30 |
| 6. 800 answers | 420 | 310 | 70 | 800 | 44 | Exact ratio 43.75 |
| 7. Detractors ahead | 18 | 22 | 40 | 80 | -28 | Exact ratio -27.5 |
| 7. Mostly passives | 8 | 70 | 22 | 100 | -14 | 70% passive, score still negative |
| 8. All promoters | 40 | 0 | 0 | 40 | 100 | One answer also scores 100 |
| 8. All detractors | 0 | 0 | 30 | 30 | -100 | Detractor share 100% |
| 8. All passives | 0 | 10 | 0 | 10 | 0 | Nothing enters the subtraction |
| 9. Passive block | 90 | 180 | 30 | 300 | 20 | 100 minus 10% detractors is 90 |
| 10. Cleaner 50 | 200 | 50 | 50 | 300 | 50 | Each side share is 16.7% |
Example 2’s 66.7 and Example 5’s 30 and Example 9’s 90 are the other arithmetic. The formula on those inputs is 40, 0, and 20.
Open the net promoter score calculator with the three counts from the export. If the export is a list of raw scores, bucket them first. 9 and 10, then 7 and 8, then 0 through 6.
A score from a week of happy customers describes that week. Churn on the same book is the post linked above. Visitors and orders are the conversion funnel post.