The Empirical Rule, sometimes called the 68-95-99.7 rule, states that for a given dataset with a normal distribution:
68% of data values fall within one standard deviation of the mean.
95% of data values fall within two standard deviations of the mean.
99.7% of data values fall within three standard deviations of the mean.
To apply the empirical rule to a given dataset, simply enter the mean and standard deviation of the dataset in the boxes below, then click the “Calculate” button.