The mean hourly rate is the average hourly wage across the entire organization so the mean gender pay gap is a measure of the difference between women’s mean hourly wage and men’s mean hourly wage.

The median hourly rate is calculated by ranking all employees from the highest paid to the lowest paid, and taking the hourly wage of the person in the middle; so the median gender pay gap is the difference between women’s median hourly wage (the middle paid woman) and men’s median hourly wage (the middle paid man).