This online calculator computes covariance between two discrete random variables. It also shows the expected value (mean) of each random variable. You can find the formula used for the calculation of covariance below the calculator.
Covariance between two discrete random variables
where E(X) is the mean of X, and E(Y) is the mean of Y.
If covariance is positive, then increasing one variable results in the increase of another variable. If covariance is negative, then increasing one variable results in the decrease of another variable. Absolute value of covariance is usually normalized by dividing by the product of the variables' standard deviations. This is the so-called Pearson correlation coefficient.