How to Calculate Net Promoter Score (Worked Examples)

Net Promoter Score (NPS) is one of the most widely used loyalty metrics in business, yet it is surprisingly easy to calculate incorrectly. The math itself is simple subtraction, but the rules about which responses count as promoters, passives, or detractors trip up a lot of teams. In this guide we walk through the exact NPS formula, show several worked examples with real numbers, and explain how to read the result so you can take meaningful action rather than chasing a vanity number.

What Net Promoter Score actually measures

NPS measures the likelihood that your customers would recommend your product, service, or brand to a friend or colleague. The premise, introduced by Fred Reichheld in 2003, is that willingness to recommend is a strong proxy for loyalty and future growth, because recommending something puts your own reputation on the line. NPS is deliberately simple so it can be tracked consistently over time and compared across teams, regions, and competitors.

It is important to understand that NPS is a relative, directional metric. A single score in isolation tells you little. Its real value comes from tracking the trend, segmenting it across customer groups, and pairing it with qualitative follow-up. If you are building a measurement program from scratch, start with our NPS survey type to get the question wording and scale right before you worry about the math.

The single NPS question

The standard NPS question is: "On a scale from 0 to 10, how likely are you to recommend [company/product] to a friend or colleague?" Respondents answer on an 11-point scale where 0 means not at all likely and 10 means extremely likely. This scale is then divided into three groups:

• Promoters (9-10): Loyal enthusiasts who will keep buying and refer others.
• Passives (7-8): Satisfied but unenthusiastic customers vulnerable to competitors.
• Detractors (0-6): Unhappy customers who can damage your brand through negative word of mouth.

Notice that passives, the 7s and 8s, are excluded from the final calculation. This is the single most common source of confusion, so keep it front of mind as we move to the formula.

The NPS formula explained

The formula is:

NPS = % Promoters − % Detractors

To compute it, you take the percentage of respondents who are promoters and subtract the percentage who are detractors. Passives are counted in the total response base (the denominator) but do not appear directly in the subtraction. The result is a whole number that can range from −100 (everyone is a detractor) to +100 (everyone is a promoter). NPS is always expressed as an integer, not a percentage, even though it is derived from percentages.

The three steps are: (1) count responses in each category, (2) convert promoter and detractor counts to percentages of the total, and (3) subtract.

Worked examples with real numbers

Example 1 — a straightforward case. Suppose you collected 200 responses:

• Promoters (9-10): 120 responses
• Passives (7-8): 50 responses
• Detractors (0-6): 30 responses

Percentage of promoters = 120 / 200 = 60%. Percentage of detractors = 30 / 200 = 15%. NPS = 60 − 15 = +45. The 50 passives are part of the 200-response base, which is why the percentages are calculated against 200 and not against 150.

Example 2 — a negative score. Imagine a smaller sample of 80 responses: 16 promoters, 24 passives, and 40 detractors. Promoters = 16 / 80 = 20%. Detractors = 40 / 80 = 50%. NPS = 20 − 50 = −30. A negative score means you have more detractors than promoters and signals an urgent retention problem.

Example 3 — rounding matters. With 150 responses: 67 promoters, 41 passives, 42 detractors. Promoters = 67 / 150 = 44.67%. Detractors = 42 / 150 = 28%. NPS = 44.67 − 28 = 16.67, which rounds to +17. Always carry the decimals through the subtraction and round only at the end; rounding each percentage first can shift the score by a point.

Example 4 — equal promoters and detractors. If 100 responses split into 30 promoters, 40 passives, and 30 detractors, then NPS = 30 − 30 = 0. A score of zero is not a failure of the survey; it means enthusiasm and dissatisfaction are perfectly balanced.

Interpreting and benchmarking your score

Because NPS ranges from −100 to +100, any positive score technically means you have more promoters than detractors. As a rough general guide, scores above 0 are considered acceptable, above 20 are favorable, above 50 are excellent, and above 70 are world-class. However, these thresholds vary dramatically by industry. Software and subscription services often post higher scores than utilities, insurance, or telecom providers, so a score of +30 might be outstanding in one sector and mediocre in another.

The most reliable benchmark is your own historical trend. Measuring the same question with the same methodology each quarter lets you see whether loyalty is improving. If you also want to benchmark against rivals, you can run a comparative study using a market research survey that includes competitor brands. Teams that need ready-made instruments can browse templates for research teams to standardize their tracking.

Common calculation mistakes

Several errors recur often enough to be worth flagging. First, excluding passives from the denominator: passives must be counted in the total response base even though they are not in the subtraction. Second, treating 7 as a promoter or 6 as a passive; the boundaries are strict at 9-10, 7-8, and 0-6. Third, averaging the raw scores instead of using the category method, which produces a completely different and incomparable number. Fourth, rounding intermediate percentages too early. Fifth, comparing scores collected with different scales or wording, which makes the comparison meaningless. Keeping the question and scale identical across waves is essential for valid trend analysis.

Turning the score into action

The score is only the start. To improve it, add an open-ended follow-up question such as "What is the main reason for your score?" and analyze the verbatim comments by category. This is sometimes called the "why" behind the number, and it is where most of the practical value lives. Route detractors to your support or success team for follow-up, and consider inviting promoters into a referral or advocacy program. Closing the loop with individual respondents, when you have their consent and contact details, often does more to raise the next score than any internal initiative. When you are ready to operationalize this, our NPS survey includes the recommended question plus the follow-up so you capture both the number and the reason in one place.

It also helps to distinguish between transactional and relationship NPS. Transactional NPS is measured right after a specific interaction, such as a support contact or a purchase, and tells you whether that moment went well. Relationship NPS is measured periodically, independent of any single event, and reflects overall sentiment toward the brand. Both are valuable, but mixing them in one number muddies the signal, so decide which you are tracking and keep it consistent. Finally, share the score and its drivers widely inside the company. A loyalty metric that only the research team sees changes nothing; a score that product, support, and leadership all watch becomes a shared goal that actually moves. The teams that improve fastest treat each wave as a feedback loop, comparing the latest result and verbatim themes against the prior period and assigning clear owners to the top one or two drivers of detraction. Comparing your trajectory against rivals, rather than against an arbitrary benchmark, keeps the focus on real competitive position instead of a number in isolation. Pairing the quantitative score with a steady stream of qualitative comments turns NPS from a backward-looking report card into a forward-looking improvement engine that guides where to invest next.

Frequently Asked Questions

Why are passives ignored in the NPS calculation? Passives (7-8) are considered neutral. They are neither loyal advocates nor active critics, so they do not add to or subtract from the score directly. They still count toward the total response base, which keeps the percentages honest.

Can NPS be negative? Yes. If detractors outnumber promoters, the score is negative, ranging as low as −100. A negative score is a strong signal that retention and satisfaction need immediate attention.

How many responses do I need for a reliable NPS? There is no fixed minimum, but small samples produce volatile scores. As a practical rule, aim for at least a few hundred responses for a stable company-level score, and be cautious interpreting segment scores built on only a handful of replies.

Should I express NPS as a percentage? No. Although it is calculated from percentages, NPS is reported as a whole number between −100 and +100, never with a percent sign.