The reference pressure in all units is designed for 1013.25 mbar. If you want to calculate the difference between 0 °C and 20 °C, e.g., the formula is as follows:
(flow at 0°C /273.15)*293.15
(Law of Boyle/Gay-Lussac)
Example: 100 ln/273.15*293.15 = 107,32 ls (=7.3%) This corresponds to a correction of 0.366 % per degree Celsius
