You can easily calculate kurtosis in Excel using the Descriptive Statistics Calculator.
Coefficient of Kurtosis
The coefficient of kurtosis, or simply kurtosis, measures the peakedness of a distribution. High kurtosis means that values close to the mean are relatively more frequent and extreme values (very far from the mean) are also relatively more frequent. The values in between are relatively less frequent. If you plot a frequency histogram or another chart showing frequency of such distribution, it would have a sharp peak in the middle and fat tails.
Conversely, low coefficient of kurtosis means that a distribution is less peaked and has thinner tails.
Coefficient of Kurtosis Formula
Coefficient of Kurtosis for a Population
Coefficient of Kurtosis for a Sample
You can see a more detailed explanation of the formulas and their underlying logic here: Kurtosis Formula.
Kurtosis is often measured and quoted in the form of excess kurtosis, which is kurtosis relative to normal distribution. The coefficient of kurtosis for normal distribution is 3, therefore excess kurtosis equals coefficient of kurtosis less 3.
Calculate Kurtosis in Excel
Here you can see more information about calculating population and sample coefficient of kurtosis and excess kurtosis in Excel.
Here you can get an Excel Calculator of kurtosis, skewness, and other summary statistics.