Normal Distribution Calculator (Probability Between Values)
Normal distribution calculator: probability that a normal variable falls below, above or between values, from the mean and standard deviation.
P(X < x) = Φ(x − μσ)
How to use this calculator
- Type your input in the box.
- The result updates as you type.
- Use “Copy result” or “Copy link” to share it.
Each value is converted to a z-score, z = (x − μ)/σ, and looked up in the standard normal distribution. About 68 % of values lie within one σ of the mean.
Frequently asked questions
IQ (mean 100, σ 15) between 85 and 115?
About 68.27 %.
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