What is the Z-Score Calculator?
A z-score tells you how many standard deviations a value is above or below the mean. A z-score of 0 is exactly average; +2 is well above average. This calculator finds the z-score and converts it into a percentile and probabilities using the normal distribution – no z-table needed.
How to use the Z-Score Calculator
- Enter the value (x), the mean (μ) and the standard deviation (σ).
- Read the z-score, percentile and probabilities.
Formula
z = (x − μ) / σ
Example
Exam score 85, class mean 70, standard deviation 10: z = 1.5 – better than about 93% of students.
This Z-Score Calculator is 100% free, needs no signup and runs privately in your browser – on phone, tablet or computer.
Last updated: · By NodifyTech