Why did my NPS go up 8 points but the calculator says it’s not significant?

Because NPS moves a lot when there are few responses. With 50 responses per group, an 8-point gap can come just from who happened to answer that month. To be sure, you need more responses.

It’s the probability of seeing a difference this large or larger if the two groups were actually the same. If it’s below 0.05, the difference is called significant at 95%.

Can I compare more than two groups?

This calculator compares two at a time. If you have several branches, try the weighted ranking, which ranks them all at once and takes into account how many responses each one has.

How do I collect more NPS responses?

With a short survey people can answer in seconds. SurvIQ has a free NPS template you can share by link, email, WhatsApp or QR code, and people respond without creating an account.

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NPS comparison calculator

Your NPS went from 32 to 38. Did you really improve, or is it chance? This calculator tells you. Enter the number of promoters, passives and detractors in each group: two months, two branches or two products.

Group A

Name (optional)

Promoters (9 and 10)

Passives (7 and 8)

Detractors (0 to 6)

Group B

Name (optional)

Promoters (9 and 10)

Passives (7 and 8)

Detractors (0 to 6)

The difference is real: it’s statistically significant at 95%.

NPS · Group A

+10

100 responses

NPS · Group B

+35

100 responses

Difference

+25

points

P-value

0.029

95% confidence interval

+2.5 to +47.5 points

The calculation runs in your browser. We don’t store what you type.

How it’s calculated

For each group, n = promoters + passives + detractors. NPS is 100 × (% promoters − % detractors), with the percentages written as proportions (pP = P / n and pD = D / n).

The variance of each group’s NPS, in squared points, is 100² × (pP + pD − (pP − pD)²) / n. It measures how much the NPS can move by chance alone.

The standard error of the difference is the square root of the sum of both variances. z = (NPS of B − NPS of A) / standard error, and the two-sided p-value comes from the normal distribution.

The 95% confidence interval is the difference ± 1.96 × standard error. The difference counts as real when the p-value is below 0.05.

How to read the result

If the confidence interval doesn’t include 0, the difference is significant: it’s very unlikely to be due to chance alone.
If the interval includes 0, you can’t say the NPS changed. That doesn’t mean nothing changed: you may need more responses to see it.
A significant difference isn’t always an important one. With many responses, a 2-point change can come out significant and still make no difference to your business.
If a group has fewer than 30 responses, take the result with care. With few responses, a single person moves the NPS a lot.

Frequently asked questions

Why did my NPS go up 8 points but the calculator says it’s not significant?: Because NPS moves a lot when there are few responses. With 50 responses per group, an 8-point gap can come just from who happened to answer that month. To be sure, you need more responses.
What is the p-value?: It’s the probability of seeing a difference this large or larger if the two groups were actually the same. If it’s below 0.05, the difference is called significant at 95%.
Can I compare more than two groups?: This calculator compares two at a time. If you have several branches, try the weighted ranking, which ranks them all at once and takes into account how many responses each one has.
How do I collect more NPS responses?: With a short survey people can answer in seconds. SurvIQ has a free NPS template you can share by link, email, WhatsApp or QR code, and people respond without creating an account.

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