By combining Boyle’s and Charles’ laws, a single expression can be derived which states all the information contained in both. The formula which is used to express the general gas law is as follows:

When using the general gas law formula, temperature and pressure must be in the absolute.

Example: 20 ft^{3} of the gas argon is compressed to 15 ft^{3}. The gas starts out at a temperature of 60°F and a pressure of 1,000 psig. After being compressed, its temperature is 90°F. What would its new pressure be in psig?