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Net Promoter Score explained for service businesses

Net promoter score is one number that shows how likely your customers are to recommend you. You ask one question, sort the answers into three groups, and subtract. A score above zero means more fans than critics. This guide shows how to ask, how to work out the score, and what to do next.

Where the idea came from

Fred Reichheld, a partner at Bain and Company, introduced the idea in the December 2003 issue of Harvard Business Review. His article was called "The One Number You Need to Grow." His point was simple. Many companies spend a lot on long satisfaction surveys, but a single question about recommending the company can tell you more about growth.

Since then, many firms have used it, from banks to clinics to consulting teams. It is popular because it is short. A customer can answer in five seconds, and you can repeat it every quarter.

Sources: Frederick F. Reichheld, "The One Number You Need to Grow," Harvard Business Review, December 2003, hbr.org.

Ask the one question

The standard question is: "How likely are you to recommend us to a friend or colleague?" Customers answer on a scale from 0 to 10. Zero means not at all likely. Ten means extremely likely.

Keep the wording the same each time. If you change the words or the scale, you cannot compare this quarter with the last one. Then add one open follow up, such as "What is the main reason for your score?" The number tells you where you stand. The reason tells you what to fix.

Sources: Bain and Company, Net Promoter System, netpromotersystem.com.

Work out the score

Sort every answer into one of three groups.

  • Promoters: scores of 9 or 10. They are loyal and likely to refer others.
  • Passives: scores of 7 or 8. They are content but could leave for a better offer.
  • Detractors: scores of 0 to 6. They are unhappy and may warn others away.

Next, turn each group into a percentage of all replies. Then subtract the detractor percentage from the promoter percentage. Passives count in the total, but they do not change the result.

Here is an example. Say 100 clients reply. Fifty give a 9 or 10, thirty give a 7 or 8, and twenty give 0 to 6. Promoters are 50 percent and detractors are 20 percent. The score is 50 minus 20, which is 30. Because it is a difference between two percentages, the score always falls between minus 100 and plus 100. Report it as a plain number, with no percent sign.

Sources: Bain and Company, Net Promoter System, netpromotersystem.com. The worked example uses made up figures to show the math.

Fit it to a service business

Service firms sell trust and people, so the timing of the question matters. Ask soon after a clear moment, such as a project handover, a closed support ticket, a finished appointment or a quarterly review. Do not ask in the middle of a dispute.

Also decide who gets asked. Send it to the person who uses your service, not only the person who signs the invoice. In a business client, those can be different people with different views.

Some practical rules help:

  • Send the survey by email or message, and keep it to two questions.
  • Ask every client on a regular schedule, not only the happy ones.
  • Do not offer a reward for a high score. It spoils the answers.
  • Never tell your staff to ask for a 10. Ask them to earn it.

If you serve a small number of clients, say 20, one reply moves the score a lot. In that case, read every comment and treat the number as a rough guide.

Act on the answers without fooling yourself

A score is only useful if it leads to action. Start with the detractors. Call each one within a few days. Listen, thank them, and fix what you can. Many unhappy clients stay when they see someone care.

Next, read the comments from all three groups and sort them into themes, such as speed, price, clarity or staff. If the same theme shows up many times, that is your first job. Then tell your team what you learned and what you will change.

Watch for these traps:

  • Chasing the number. A better score is a sign, not the goal. The goal is happier clients.
  • Changing the sample. If you only survey your best clients this quarter, the score will rise for the wrong reason.
  • Comparing across industries. A good score in one field may be average in another. Compare against your own past results first.
  • Ignoring the passives. They are the largest group in many firms, and a small improvement can turn them into promoters.

Sources: Bain and Company, Net Promoter System, netpromotersystem.com. The traps and the follow up steps are the editors' practical suggestions, not research findings.

Start this month

Pick one moment in your client journey and send the question after it. Record the score, sort the comments, and call your detractors. Repeat every quarter with the same wording. After two or three rounds, you will see whether your changes are working.

Net promoter score is not a full picture of your business. Use it alongside renewals, repeat work and direct client feedback. Used that way, one simple question can show you where to improve first.

Sources: Frederick F. Reichheld, "The One Number You Need to Grow," Harvard Business Review, December 2003, hbr.org. Bain and Company, Net Promoter System, netpromotersystem.com.