NPS Calculator
Free tool · by Daniel HaketTurn survey responses into a single loyalty number. Enter your promoters, passives and detractors and this calculates your Net Promoter Score — the standard measure of how likely customers are to recommend you.
What this free tool is great for: a quick, one-off job with no signup — it runs entirely in your browser, so nothing leaves your device and there's nothing to manage.
Its honest limit: it works the number out once, by hand — it won't pull your live data, trend it over time, or flag when it shifts, so it's a snapshot rather than a dashboard.
How NPS works
Net Promoter Score comes from one question — how likely are you to recommend us, on a 0 to 10 scale — and sorts every answer into one of three groups: promoters (9–10), passives (7–8) and detractors (0–6). The score is the percentage of promoters minus the percentage of detractors, so it can land anywhere from -100 to +100. Passives count in the total but not in the subtraction, which is why a crowd of lukewarm customers pulls the score toward zero without ever showing up as a problem.
You will often read that anything above 0 is positive and above 50 is excellent; treat those as rules of thumb, because what counts as good differs a lot between industries, countries and the way the question is asked.
A worked example
Say 100 customers answer: 60 give a 9 or 10, 30 give a 7 or 8 and 10 give 6 or lower. Promoters are 60% of the total and detractors 10%, so the score is 60 minus 10, which is 50. Now suppose ten of those passives become promoters: promoters rise to 70%, detractors stay at 10%, and the score moves to 60 without a single unhappy customer changing their mind.
Suppose instead that ten passives slide into detractors: the score falls to 40. The same thirty people in the middle can move the headline in either direction, which is why the calculator above shows all three groups and not just the final number.
The trend beats the number
An absolute score is hard to interpret on its own: it depends on your industry, your customers' culture and how you phrase and time the question. What you can act on is your own trend, measured the same way each time. A score that climbs from 20 to 35 over a year tells you more than a competitor's published 40, because you know how your number was collected and you do not know how theirs was.
Chasing someone else's benchmark is a distraction; beating your own last quarter, with the same method, is the useful goal.
Reading the three groups honestly
The categories carry information beyond the headline. Promoters are the customers most likely to refer others and to expand, so they are worth asking for a review or a referral rather than only counting. Passives are satisfied but not attached: they do not lower the score, but they are the group most likely to leave quietly for a better offer, and often one fixed annoyance separates them from becoming promoters.
Detractors are both a risk and a gift — a risk because they may churn or speak badly of you, a gift because many of them are telling you, before they go, what is broken. A team that only watches the aggregate score throws away most of what the survey collected: who is in each group and why.
The comment is where the value is
The follow-up question — "what is the main reason for your score?" — is where NPS earns its keep. The number tells you that something changed; the comments tell you what. Read them unfiltered on a fixed rhythm, tag them into a handful of themes such as pricing, support speed or a missing feature, and watch which themes grow. When several detractors independently name the same specific thing, it has stopped being an anecdote.
Then close the loop: reply to detractors personally and without defensiveness, say what you will do, and give every detractor response an owner and a deadline. Thank promoters too, and ask the ones who are willing for a review or a referral. Teams that survey without ever answering teach customers that feedback disappears, and that makes later surveys less useful.
Survey mechanics shape the score
The same customers can give you a noticeably different score depending on how you ask. Timing matters: surveying right after a successful onboarding tends to flatter the result, and surveying straight after a support ticket tends to depress it; a steady rhythm that does not follow good or bad moments gives a fairer picture. The channel matters as well: an in-app prompt reaches your most active users, while email also reaches the quieter ones.
And the people who answer are not a random sample of your customers — those with strong feelings in either direction are more likely to respond. A higher response rate helps, but on its own it does not prove the answers represent everyone, so look at who did not answer before you trust a movement. Above all, keep the mechanics the same from one round to the next, or your trend measures the change in method rather than the change in customers.
Small samples move a lot
Each response is worth 100 divided by the number of responses in percentage points. With 40 answers, one person is 2.5 points, and one detractor who becomes a promoter moves the score by 5 points, because it removes 2.5 from the detractor share and adds 2.5 to the promoter share. With 400 answers the same change moves the score by half a point. So when your sample is small, a jump of five or ten points can be one or two people changing their mind, not a shift in how your customers feel.
Before you celebrate or worry, check how many responses the score rests on and whether the change survives the next round. For planning how many responses you need, the survey sample size calculator gives a starting point.
Relationship NPS versus transactional NPS
One acronym, two instruments. Relationship NPS — the periodic "how likely are you to recommend us overall" — measures the health of the whole relationship and moves slowly. Transactional NPS is asked after a specific event, such as a closed support ticket or a delivered order, and measures that touchpoint. Mixing the two into one trend line creates noise that looks like signal: a month with many support tickets can pull the blended score down whatever customers think of you overall.
Run them separately with separate baselines. For most small businesses a periodic relationship survey plus short transactional pulses on the one or two touchpoints that matter most is enough; asking more often than that risks tiring the very customers you are measuring.
Where NPS misleads
Treat NPS as a directional signal, not as the metric that runs the business. It is easy to game — survey only happy customers, or ask right after a win — and the pressure to hit a target makes that tempting. One blended number can hide an audience that is split, with some customers delighted and others frustrated. And the score says nothing about why on its own. Use it to spot movement and to collect reasons, alongside retention, support and revenue figures that measure what customers actually do.
Frequently asked questions
What is a good NPS score?
Anything above 0 means you have more promoters than detractors. Rules of thumb call scores above 50 excellent, but benchmarks vary widely by industry and by how the question is asked, so your own trend, measured the same way each time, is the better yardstick.
How is NPS calculated?
Percentage of promoters (9–10) minus percentage of detractors (0–6). Passives (7–8) count toward the total but not the score. This tool does the maths.
How many responses do I need?
More than you might think for small changes to mean anything. Each response is worth 100 divided by your number of responses in points, so with 40 answers one customer switching from detractor to promoter moves the score by 5 points.
How do I collect NPS responses?
Send the 0–10 recommendation question to customers with a survey tool like SurveyMonkey, then drop the counts in here.
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