Z-Score Calculator
Turn a value into a z-score (standard score) and find the share of a normal distribution below and above it.
Z-score
1.5
- P(X < x) — percentile
- 0.9331927987 (93.31928%)
- P(X > x)
- 0.06680720127 (6.6807201%)
- Two-tailed p-value
- 0.1336144025 (13.36144%)
Show the work
Distance from the mean
x − μ
85 − 70 = 15
Divide by the standard deviation
z = (x − μ) ÷ σ
15 ÷ 10 = 1.5
How it works
z = (x − μ) ÷ σ; P(X < x) = Φ(z), the standard normal CDF
Questions
- How does the z-score calculator work?
- z = (x − μ) ÷ σ; P(X < x) = Φ(z), the standard normal CDF.
- What do I need to enter?
- Value (x), Mean (μ), Standard deviation (σ). Optional fields can be left blank.
Related tools
- Percentile CalculatorFind the value at any percentile of a data set, and the percentile rank of a value.
- Quartile & Five-Number Summary CalculatorGet the quartiles, interquartile range (IQR), five-number summary and outliers of a data set.
- Confidence Interval CalculatorFind the confidence interval for a mean from the sample mean, standard deviation and sample size.
- Sample Size CalculatorFind how many people to survey (or measurements to take) for a chosen margin of error and confidence level.
- Margin of Error CalculatorFind the margin of error of a survey result or a sample mean at a chosen confidence level.
- Probability CalculatorCombine the probabilities of two events: both, either, neither, exactly one, and not A.
Want this on your site? Embed the z-score calculator.