How fast do air molecules move at 20 °C?

At 20 °C, the root-mean-square speed ($v_{rms}$) of air molecules is 502 metres per second (m/s).1

This value is derived from the kinetic theory of gases, which relates the temperature of a gas to the average kinetic energy of its molecules. The $v_{rms}$ is calculated using the formula:

$$v_{rms}=\sqrt{\frac{3RT}{M}}$$

In this equation, $R$ is the gas constant, $T$ is the absolute temperature in kelvins, and $M$ is the molecular weight of the gas.1