How to Calculate NPS
The NPS formula explained step by step with worked examples. Calculate your own NPS with our free tool.
The NPS formula
NPS is a single subtraction:
NPS = % Promoters - % Detractors
You survey customers with one question: “How likely are you to recommend us to a friend or colleague?” They answer on a 0 to 10 scale, and their response puts them into one of three groups:
- Promoters (9 to 10): loyal customers who actively recommend you
- Passives (7 to 8): satisfied but unenthusiastic, easily pulled away by a competitor
- Detractors (0 to 6): unhappy customers who may discourage others from using your product
Calculate the percentage of respondents in the promoter group, subtract the percentage in the detractor group, and that’s your NPS. The result ranges from -100 (every respondent is a detractor) to +100 (every respondent is a promoter).
Step-by-step calculation
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Collect responses. Send your NPS survey and gather scores from 0 to 10. You need enough responses for the result to be meaningful. Below 50 is shaky. Above 100 is solid.
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Sort into groups. Count how many respondents scored 0 to 6 (detractors), 7 to 8 (passives), and 9 to 10 (promoters).
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Calculate percentages. Divide each group count by the total number of responses, then multiply by 100.
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Subtract. Take the promoter percentage and subtract the detractor percentage. Ignore passives for this step. They affect the percentages indirectly (by inflating the denominator) but don’t appear in the formula itself.
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Round. NPS is conventionally expressed as a whole number. Round to the nearest integer.
Worked example
Say you survey 200 customers. The responses break down like this:
| Group | Score range | Count | Percentage |
|---|---|---|---|
| Detractors | 0 to 6 | 40 | 20% |
| Passives | 7 to 8 | 60 | 30% |
| Promoters | 9 to 10 | 100 | 50% |
NPS = 50% - 20% = 30
An NPS of 30 puts you roughly in line with the SaaS average, which sits around 30 to 40. Not bad, but there’s room to grow.
Now imagine 20 of those passives had scored you a 9 instead:
| Group | Score range | Count | Percentage |
|---|---|---|---|
| Detractors | 0 to 6 | 40 | 20% |
| Passives | 7 to 8 | 40 | 20% |
| Promoters | 9 to 10 | 120 | 60% |
NPS = 60% - 20% = 40
A 10-point jump from converting passives alone. This is why the passive group deserves attention even though it doesn’t appear in the formula.
Using our free NPS calculator
Rather than running the maths yourself, plug your numbers into our NPS calculator. Enter the number of respondents for each score from 0 to 10, and it calculates your NPS instantly with a benchmark comparison.
It’s useful for modelling scenarios too. You can see how your score changes if you convert a handful of detractors into passives, or passives into promoters. That kind of “what if” thinking helps prioritise where to focus your retention efforts.
Common calculation mistakes
Averaging scores instead of using the formula. NPS is not the mean of all responses. Averaging 0 to 10 scores gives you something, but it’s not NPS. The formula specifically uses the difference between two group percentages.
Treating passives as half-promoters. Some teams assign partial credit to passives or weight them somehow. The standard NPS methodology ignores them in the subtraction. If you modify the formula, you’re no longer calculating NPS. You’re calculating something else.
Mixing survey populations. Combining NPS from free trial users with paying customers, or mixing onboarding surveys with renewal surveys, muddies the result. Segment your data. NPS from a customer in month one means something different to NPS from a customer in year three.
Rounding percentages before subtracting. Small rounding errors in the percentages can shift the final score by a point or two. Calculate with precise percentages first, then round the final NPS.
How often to measure NPS
Most SaaS companies survey quarterly. That gives enough time for product changes to show up in scores while keeping the data fresh enough to act on.
Some teams run continuous or “always on” NPS. They sample a portion of their customer base each week and report on a rolling 90-day average. This smooths out noise and lets you spot trends earlier, but it requires enough customers to sustain a steady flow of responses without surveying anyone too often.
Whatever cadence you choose, resist surveying the same customer more than once per quarter. Survey fatigue drags down response rates and biases results toward your most engaged users.
Timing within the customer lifecycle matters too. NPS measured right after onboarding captures first impressions. NPS before renewal captures the decision-making moment. Both are useful, but they answer different questions and shouldn’t be mixed in the same score.
What to do with your score
A number on its own doesn’t fix anything. The value of NPS comes from what you do with the responses.
Follow up with detractors. A score of 0 to 6 is a signal, but you need to know why. A short open-ended follow-up (“What could we do better?”) turns a number into something you can act on. Some teams route detractor responses directly to customer success for outreach.
Understand your passives. They’re often overlooked because they don’t appear in the formula, but passives are the easiest group to move. They’re already using your product. They just aren’t excited about it. Find out what’s missing.
Don’t forget the other half. NPS only measures sentiment. It says nothing about customers whose payments fail silently. That’s involuntary churn, and it accounts for 20 to 40% of all SaaS churn. A customer who scores you a 10 today can still disappear next month if their card expires. Pair your NPS programme with dunning recovery to cover the side of churn that surveys can’t see.