The Combined Gas Law  associates the pressure, volume, temperature and a constant of a gas, based on a combination of Charles's law, Boyle's law, and Gay-Lussac's law. There is no 'official' founder for this law because it is a consolidation of the three other laws.  The combined gas law states the ratio between the pressure-volume product and the temperature of a system remains constant (k).  The units of k are typically in Joules per degree Kelvin (J/K).  This constancy can be used when comparing different conditions using the same substances. The combined gas law is mathematically expressed as follows:

`(P_i V_i)/(T_i) = (P_(f) V_f)/(T_f) = k`

The Combined Gas Law calculator groups the forms of the Combined Gas Law formula in two ways as follows:

P • V / T = k 

• Pressure based on known volume, temperature and the combined gas constant.
• Volume based on know pressure, temperature and the combined gas constant.
• Temperature based on known pressure, volume and the combined gas constant.
• k gas constant based on the proportionality of the gas if you know pressure, volume and the temperature for the specific gas.

P_i • V_i/T_i = P_f • V_f/T_f

Since P•V/T = k, one can compute the initial (i) and final (f) states using the expanded version of the Combined Gas Law. The formula P_i • V_i/T_i = P_f • V_f/T_f allows the user to enter any five of the six values in the formula to compute the remaining one attribute via the Combined Gas Law.

• Final Pressure based on an initial and final temperature and volume and an initial pressure.
• Final Temperature based on an initial and final pressure and volume and an initial temperature.
• Final Volume based on an initial and final pressure and temperature and an initial volume.