For a symmetric distribution, the height and sharpness of the peak relative to the rest of the data is measured through a number called Kurtosis. A high kurtosis value indicates a distinct peak near the mean and fatter tails while a lower or negative kurtosis value indicates wider peak around mean and thinner tails.
The formula for excess kurtosis is given by:
Where indicates various data points, Y is mean of data, n is the number of data points and s is the standard deviation.
A positive value indicates a peaked distribution and a negative value indicates a flat distribution. The value of kurtosis for a standard normal distribution is 3.