Calculator of gas volume or flow in different conditions of pressure and temperature


The volume occupied by a given quantity of gas is a function of its temperature and pressure. This calculator provides an easy way to calculate the new volume (or flow) occupied by a gas when the pressure and/or temperature changes. As flow is volume per unit of time, it can also be used to calculate flow.

The calculator considers that gas behaves as an ideal gas. This is usually a good approximation, and it is enough in most cases.

The equation used is the following: V2 = (P1 · V1 · T2) / ( P2 · T1)

In the case of flow: Q2 = (P1 · Q1 · T2) / ( P2 · T1)

P= Pressure
V= Volume
Q= Flow
T= Temperature (ºK)

Pressure, volume and flow can be entered in any unit, as long as the same unit is used for both cases. Pressure is absolute, not relative.


- Known values:

  V1 o Q1:



- Pressure and temperature for which you want to calculate volume or flow:




  V2 o Q2:


Example 1: A diver has an air bottle that contains 25 liters at a pressure of 10 atm and 20ºC. If we enter these data as known values and taking into account that usually it is considered 0ºC and 1 atm as normal conditions, we enter P2=1 y T2=0ºC, and get a value of V2=232.9 liters.

Example 2: The flow in a pipe is 75m3/h at a absolute pressure of 2500 kPa and 50ºC. We can calculate that at atmospheric pressure (101.3 kPa) and ambient temperature of 25ºC, that the gas flow would be 1707.7 m3/h.

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