Net Promoter Score (NPS): Formula and Use in a Small Shop

By Alva Chew · Updated 2026-11-06

Definition Net Promoter Score (NPS) is the percentage of customers who answer 9 or 10 to a 0 to 10 'would you recommend us' question, minus the percentage who answer 0 to 6. It runs from -100 to +100. For a café or shop, it only means something if you measure it the same way each time and compare it with your own past scores.

What is Net Promoter Score?

Net Promoter Score, or NPS, is a single number built from one survey question. You ask customers how likely they are to recommend your business to a friend or colleague, and they answer on a scale from 0 to 10. The result is a score between -100 and +100.

Net Promoter, Net Promoter Score and NPS are registered trademarks of Bain & Company, Fred Reichheld and Satmetrix Systems, according to Bain’s own description of the system (December 2011).

How is NPS calculated?

Bain groups the answers into three bands and subtracts one share from the other.

Answer	Group	Counts in the score
9 or 10	Promoters	Added
7 or 8	Passives	Only in the total number of answers
0 to 6	Detractors	Subtracted

Source: Bain & Company, Introducing the Net Promoter System, 8 December 2011. Bain words the question as “How likely is it that you would recommend [product, service or company/brand] to a friend or colleague?”

Formula: NPS = % promoters minus % detractors.

Worked example with made-up numbers: 100 customers answer. 60 give a 9 or 10, 25 give a 7 or 8, and 15 give 0 to 6. That is 60% minus 15%, so your NPS is +45. The 25 passives changed nothing except the total.

How do you collect NPS in a café, restaurant or shop?

Keep the survey short and ask it the same way every time. Two choices matter most:

Who you ask. Ask real customers soon after a purchase, not only the ones who already like you.
When you ask. Pick a fixed rhythm such as once a month, so scores can be compared.

Bain’s method adds a follow-up asking for the main reason behind the score, and the reasons are usually more useful than the number. A customer who gives a 6 and says “the queue was long on Saturday” has told you something you can act on.

Why can an NPS be misleading?

The people who answer a survey are often not typical of the people who do not. Bain gives an example in Creating a reliable metric.

Group	Share of customers	Result
Respondents	20%	60% promoters, 10% detractors, NPS 50
Nonrespondents	80%	10% promoters, 40% passives, 50% detractors, NPS -40
Weighted together	100%	NPS of about -22

Source: Bain & Company, Creating a reliable metric. The numbers are Bain’s illustration, not a measured result. Bain treats response rates below 40% for consumer businesses as a red flag.

For a small shop, this matters because a handful of enthusiastic regulars can produce a high score while quieter customers drift away. Report how many customers you asked and how many replied next to the score.

How does NPS relate to retention and repeat purchases?

NPS records what customers say they would do. Customer retention rate and repeat purchase rate record what they did. Track both. If your NPS rises while the number of customers who come back stays flat, the survey is telling you something your till is not confirming.

Where does a loyalty program fit?

A loyalty program gives each customer an account, so you can send the survey to a known group and compare members with people who never joined. Read the result next to redemption rate, and see the guide on measuring loyalty program success for the other numbers worth tracking.

Using it with Gimify

Gimify gives each member one points balance across every outlet, so a member who uses two of your branches is still one person when you compare groups. The free plan covers one outlet with unlimited members.

Questions owners ask

How do I calculate Net Promoter Score?

Ask customers how likely they are to recommend you on a 0 to 10 scale. Count 9 and 10 as promoters and 0 to 6 as detractors. Subtract the detractor percentage from the promoter percentage. Passives (7 and 8) only count in the total number of answers.

What is a good NPS for a café or shop?

There is no single good number, and a benchmark from a different industry says little about your shop. Measure your own score for a few months, then judge changes against that baseline.

Can NPS be negative?

Yes. The score is a difference between two percentages, so it runs from -100 to +100. A negative score means you have more detractors than promoters among the people who answered.

How many responses do I need?

Bain says a response rate below 40% for consumer businesses is a red flag, because the people who answer can differ from the ones who do not. With a small customer base, the share who replied matters as much as the count.

Is NPS the same as customer satisfaction?

No. NPS asks one question about recommending you. Satisfaction surveys ask how happy a customer was with a visit or a product. The two can move differently, so do not swap one for the other.

Can I use NPS to judge my loyalty program?

Only as one signal. Compare the score of members and non-members, and read it next to behaviour such as redemption rate and repeat purchase rate, because what customers say and what they do can differ.