How is the total pressure of a gas mixture calculated from partial pressures?

The total pressure of a gas mixture is calculated using Dalton’s law, which states that the total pressure is equal to the sum of the partial pressures of each individual component gas in the mixture.1

A partial pressure is defined as the pressure that a specific gas would exert if it alone occupied the entire volume of the mixture at the same temperature. This relationship assumes that the gases behave as ideal gases and do not chemically interact with one another. Under the kinetic theory of gases, this additive property occurs because the impacts of different molecular species against the container walls contribute to the total pressure independently. While this law is most accurate for ideal gases, it remains a valid approximation for real gases at high temperatures and low pressures.123