Natural gas is compressible, so its volume changes with pressure and temperature. That is why measurements are often referred to common reference conditions.
Actual volume
It is the volume at the actual conditions of the measurement point.
Reference volume
It is the same volume corrected to a predetermined pressure and temperature so that measurements are comparable.
Why it matters
At higher pressure, the same amount of gas occupies a smaller actual volume. Without correction, two m³ readings may not correspond to the same amount of gas.
Practical use
Standard conditions are used in technical calculations, energy monitoring, and commercial metering.
