# Harmonic mean > The harmonic mean gives us a way to find the average of a set of values that emphasizes the smaller numbers in the set, making it particularly useful when averaging rates or ratios, like speeds or densities. The harmonic mean gives us a way to find the average of a set of values that emphasizes the smaller numbers in the set, making it particularly useful when averaging rates or ratios, like speeds or densities. $$ \text{Harmonic Mean} = \frac{n}{\frac{1}{x_1} + \frac{1}{x_2} + \dots + \frac{1}{x_n}} $$