Normal Interval Probability Calculator
Estimate the probability within an interval of a specified normal distribution.
Your result
MATHEnter your values and select calculate.
On this page How it works & practical examples
How to use the Normal Interval Probability Calculator
Enter the distribution parameters and both endpoints on the same measurement scale. The tool evaluates a normal CDF approximation and shows the complementary outside probability.
The calculation
Worked example
A standard normal distribution between −1 and 1 has about 68.2689% probability.
Assumptions and limits
The model assumes a normal distribution; it is not a normality test or a confidence interval. The CDF approximation has small numerical error, and extreme tails may display as zero.
Common questions
Which inputs should I use?
Enter the distribution parameters and both endpoints on the same measurement scale. The tool evaluates a normal CDF approximation and shows the complementary outside probability.
What does the result exclude?
The model assumes a normal distribution; it is not a normality test or a confidence interval. The CDF approximation has small numerical error, and extreme tails may display as zero.