- • P is the pressure of the gas
- • V is the volume of the gas
- • m (n) is the amount of substance of gas (also known as number of moles)
- • R is the ideal, or universal, gas constant, equal to the product of the Boltzmann constant and the Avogadro constant.
- • T is the temperature of the gas
In SI units, P is measured in pascals, V is measured in cubic metres, n is measured in moles, and T in kelvins (273.15 kelvins = 0.00 degrees Celsius). R has the value 8.314 J·K−1·mol−1 or 0.08206 L·atm·mol−1·K−1 if using pressure in standard atmospheres (atm) instead of pascals, and volume in liters instead of cubic metres.