NPS and Customer Satisfaction Calculator

A Net Promoter Score of +30 from sixty replies is also, on the same data, anywhere between +10 and +50. Every dashboard prints the +30.

This prints both, with the range in the tile immediately beside the score, because that range is what decides whether next quarter’s number means anything. On sixty replies it is about forty points wide — which makes a three or five point movement exactly what you would expect from asking the same people again.

It also shows how many replies would be needed to get the range down to a width you would actually act on, and the answer is usually in the high hundreds. Halving a range costs four times the replies. That is not a discouragement, it is the number worth knowing before a quarterly target gets set on a score that cannot support one.

Underneath is the thing about NPS that surprises people: sevens and eights count for nothing. A company that moved every single detractor up to a seven would see no improvement in its score at all. So the mean of the raw answers is on the page beside it, using every reply, and the two can move in opposite directions.

There is no industry benchmark anywhere on it. Published NPS figures are collected with different wording, at different moments, from differently chosen people, and comparing yourself to one is how a target gets set that means nothing. The only fair comparison is your own last round, which is why saving them is the point.

And it says the thing no arithmetic can fix: if the people who reply are the ones with something to say, no interval on the page repairs that.

Save as many versions as you like and put any two side by side, figure against figure, with the better one on each line marked and the difference in its own column. That screen is the one that decides things, and it is the part a free calculator cannot do at all. Two rounds whose ranges overlap have not moved, whatever the two scores say.

One HTML file. No account, no subscription, no internet needed. Opens on Windows, Mac and Android; the readme explains the extra step on iPhone and iPad, where Apple blocks JavaScript in downloaded files and every tool of this kind is affected.

Everything lives in your browser on your device. Nothing is uploaded, which is why it works offline and why nobody else can see your figures — and it also means clearing your browsing data deletes it. The tool does not pretend otherwise: the header shows how long since your last export at all times, turns amber after three days and red after seven, and export is one click that produces a plain file you keep.