Net Promoter Score (NPS): Formula and Benchmarks
Net Promoter Score explained: the NPS formula, a worked example, what counts as a good score, B2B benchmarks, survey timing and how to act on detractors.
Net Promoter Score (NPS) measures customer loyalty with one question: "How likely are you to recommend us to a friend or colleague?" on a 0 to 10 scale. You subtract the percentage of detractors (0-6) from the percentage of promoters (9-10) to get a score between -100 and +100. Above zero is positive, above +50 is strong, and the most useful benchmark is your own score tracked over time.
For a small business, NPS is less about the number and more about what it starts: a short conversation with unhappy clients before they leave, and a list of happy clients ready to give referrals or testimonials. This guide covers the formula, a worked example, benchmarks, how to run the survey, and what to do with the results.
Where NPS comes from
Fred Reichheld of Bain & Company introduced the metric in the December 2003 Harvard Business Review article "The One Number You Need to Grow." His argument was that willingness to recommend predicted repeat business and growth better than long satisfaction questionnaires. Net Promoter is a registered trademark associated with Bain, Reichheld and Satmetrix. The metric is widely used, but researchers have questioned whether it predicts growth better than ordinary satisfaction measures, so treat it as one useful signal rather than a complete picture.
The Net Promoter Score formula
NPS = % promoters - % detractors
| Group | Score given | What it usually means |
|---|---|---|
| Promoters | 9-10 | Loyal, likely to buy again and refer others |
| Passives | 7-8 | Satisfied but could switch to a competitor |
| Detractors | 0-6 | Unhappy; at risk of leaving or complaining |
Passives count in the total number of responses but are not added or subtracted. NPS is reported as a whole number, not a percentage: "+32," not "32%."
Worked example: calculating NPS for a small agency
An illustrative example. A marketing agency surveys its 60 active and recent clients after their projects close or at their retainer anniversary. 40 reply.
| Group | Responses | Share of 40 |
|---|---|---|
| Promoters (9-10) | 22 | 55% |
| Passives (7-8) | 11 | 27.5% |
| Detractors (0-6) | 7 | 17.5% |
NPS = 55% - 17.5% = 37.5, reported as +38 (rounded).
Look at the comments next. Four of the seven detractors mention the same thing: invoices arrive with unclear line items and they have to email to ask what each charge covers. That is not a marketing problem, and it is cheap to fix. The agency switches to itemized invoices that match the scope in each proposal. Six months later, with a similar sample, two of those clients have moved to passive and the score is +45.
Notice how sensitive small samples are: with 40 responses, each client moving from detractor to promoter shifts the score by 5 points. Always report the response count with the score.
What is a good Net Promoter Score? Benchmarks
Benchmarks depend heavily on industry, survey method and who is asked, so use them as context only.
| NPS range | Rough interpretation |
|---|---|
| Below 0 | More detractors than promoters; investigate urgently |
| 0 to +30 | Positive, but room to improve |
| +30 to +50 | Solid for most service businesses |
| +50 to +70 | Strong; customers actively recommend you |
| Above +70 | Exceptional; rare at scale |
For business-to-business service firms, ClearlyRated's B2B services benchmark research reported industry NPS hovering around +40 from 2021 to 2023. Small, owner-led firms often score higher than large companies because clients deal directly with the person doing the work, but a small sample can also flatter you. Compare against yourself first.
How to run an NPS survey step by step
- Decide when to ask. After a project closes, after the final invoice is paid, or every 6-12 months for ongoing clients.
- Keep it to two questions. The 0-10 recommendation question, then "What is the main reason for your score?" as an open text box.
- Choose a tool. A free form tool works, and many CRMs and email platforms include NPS survey features.
- Send from a real person. A short personal note gets more replies than a no-reply survey link.
- Calculate the score and tag each comment by theme: price, quality, speed, communication, billing.
- Close the loop. Reply to every detractor within a few days and thank every promoter.
- Repeat on the same schedule and wording so scores are comparable.
Sample NPS email
Subject: One quick question about [project]
Hi [Name], thanks for working with us on [project]. On a scale of 0-10, how likely are you to recommend us to a friend or colleague? Just reply with a number, and if you have a moment, tell us the main reason. Every reply is read by me personally. - [Your name]
What to do with promoters, passives and detractors
| Group | Follow-up action | Timing |
|---|---|---|
| Promoters | Thank them; ask for a testimonial, review or referral | Within a week |
| Passives | Ask what would make it a 9 or 10 | Within two weeks |
| Detractors | Personal call or email; acknowledge, fix if possible | Within 48 hours |
Promoters are your best source of social proof. Our testimonial request email templates are designed for exactly this moment, and the same promoters are the best people to ask for an online review. Do not offer rewards only to people who promise a positive review; the FTC's 2024 rule on consumer reviews prohibits incentives conditioned on sentiment.
Detractors are your early warning system. A detractor you call personally sometimes becomes your most loyal client, because few businesses bother. Common root causes include missed deadlines, scope disagreements and billing confusion. If billing is the issue, tightening your client onboarding process so payment terms are agreed up front often fixes it.
NPS and revenue: why the score matters financially
NPS is a leading indicator. Detractors are more likely to cancel, which shows up later as churn, while promoters tend to stay longer, buy more and refer others, raising customer lifetime value. A practical way to connect the two is to tag each client in your records with their latest NPS group, then compare a year later: what share of detractors renewed versus promoters? That one comparison tells you how much a point of NPS is worth to your business.
Relationship NPS vs transactional NPS
There are two common ways to run the survey, and they answer different questions.
| Relationship NPS | Transactional NPS | |
|---|---|---|
| When it is sent | On a schedule, such as every 6 or 12 months | Right after a specific event: project delivery, support ticket, first invoice |
| What it measures | Overall loyalty to your business | How one touchpoint shaped their view |
| Best for | Retainers, subscriptions, long-term clients | Project work and finding weak steps in your process |
| Risk | Slow to show the effect of changes | Can swing with one bad day |
Most small businesses should start with one of these, not both. A project-based freelancer gets the most from a transactional survey sent once the final invoice is paid, while a business with monthly retainer clients is better served by a yearly relationship survey.
What to do if your NPS drops
- Check the sample first. Did fewer people reply, or did a different type of client reply? A drop from +45 to +30 on 15 responses may be noise.
- Read every detractor comment from the period and group them by theme.
- Look for a recent change: a price increase, a new team member, a slower turnaround, a new billing system.
- Call the detractors. Ask what happened and what would fix it. Some problems, such as a late or confusing invoice, are quick to put right.
- Tell clients what you changed. A short note saying "you told us X, so we did Y" earns goodwill and more honest feedback next time.
Sometimes a low score reveals a client who is simply a poor fit, someone whose expectations or budget you cannot meet. In that case, ending the relationship politely may be better for both sides; our guide on how to fire a client covers how to do it professionally, including the final invoice. And if detractor comments keep mentioning billing disputes, review how you track what clients owe in your accounts receivable process.
Common NPS mistakes
- Chasing the number. Asking clients to "please give us a 10" makes the score meaningless.
- Surveying only happy clients. Cherry-picking inflates the score and hides problems.
- Ignoring comments. The reason behind the score is more valuable than the score.
- Changing the question. Altered wording or scales break comparisons over time.
- Comparing across industries. A +30 for an internet provider and a +30 for a boutique agency mean different things.
- Not closing the loop. Customers stop responding if nothing ever changes.
NPS alongside other metrics
NPS works best with a few hard numbers: churn or retention rate, repeat purchase rate, average days to pay, and revenue per client. Our guide to financial ratios for small business covers the money side. If clients who rate you highly also pay faster and renew more, you have strong evidence that service quality drives profit.
Billing is part of the experience clients rate. Clear, itemized invoices that match what was agreed remove one of the most common sources of detractor comments. Create professional invoices with our free invoice generator, with no sign-up needed, and download them as PDFs ready to send.
Frequently asked questions
How do you calculate Net Promoter Score?
Ask customers how likely they are to recommend you to a friend or colleague on a 0 to 10 scale. Count 9s and 10s as promoters, 7s and 8s as passives, and 0 to 6 as detractors. Subtract the percentage of detractors from the percentage of promoters. For example, 50% promoters minus 20% detractors gives an NPS of +30. Passives count in the total responses but not in either group.
What is a good Net Promoter Score?
Any score above zero means you have more promoters than detractors. As a rough guide, above +30 is solid, above +50 is strong and above +70 is exceptional. Benchmarks vary by industry and survey method: B2B services benchmarks from ClearlyRated have hovered around +40 in recent years. The most useful comparison is your own score over time, measured the same way, rather than another company's number.
Can Net Promoter Score be negative?
Yes. NPS ranges from -100, where every respondent is a detractor, to +100, where every respondent is a promoter. A negative score means more customers gave 0 to 6 than 9 or 10. That is a warning sign worth investigating through follow-up conversations, especially if detractors share common complaints such as slow delivery, billing errors or poor communication. Fixing the top complaint usually moves the score more than any campaign.
How many responses do I need for a reliable NPS?
There is no fixed minimum, but scores from small samples swing a lot. With 20 responses, one client moving from a 6 to a 9 changes your score by 10 points. Small businesses should treat NPS as a conversation starter and look at the comments behind each score. Track a rolling 12-month figure rather than reacting to one month, and report the number of responses alongside the score.
How often should a small business send an NPS survey?
For project-based services, send it once after each project closes or the final invoice is paid. For ongoing clients and subscriptions, a survey every six or twelve months is enough. Surveying too often causes fatigue and lower response rates. Avoid sending it right after a billing dispute or support issue unless you specifically want transactional feedback on that interaction.
Who created Net Promoter Score?
Fred Reichheld of Bain and Company introduced Net Promoter Score in a December 2003 Harvard Business Review article titled 'The One Number You Need to Grow.' It was developed with Bain and Satmetrix, and Net Promoter is a registered trademark. The idea was that a single recommendation question predicts growth and loyalty. Researchers have since debated how well it predicts growth compared with other satisfaction measures.
What is the difference between NPS and CSAT?
Net Promoter Score measures overall loyalty and willingness to recommend, using a 0 to 10 scale and the promoter-minus-detractor formula. Customer satisfaction score, or CSAT, measures satisfaction with a specific interaction, such as a support call or delivery, usually on a 1 to 5 scale, reported as the percentage of satisfied responses. Many businesses use CSAT after individual touchpoints and NPS for the relationship overall.
Invoice Creator Editorial Team
Guides on invoicing, cash flow and small-business finance from Invoice Creator, operated by Next Software Development Company. Content is reviewed for accuracy against the fields our own invoice generator produces.
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