Gas volumes are commonly referred to in "standard" or "normal" units. Standard conditions commonly refers to gas volumes measured at: Metrics: 15°C and 101.3250 kPa Field: 60°F and 14.696 psia

These P & T conditions are often indicated as Standard Temperature and Pressure, abbreviated to STP. However standard conditions can refer to other combinations of pressure and temperature as might be agreed between gas buyer and seller.

Calculation Input


Volume occupied:

At Standard conditions

std m3 (15°C, 101.3250 kPa)
std ft3 (scf) (60°F, 14.696 psia)

At Normal conditions (or Normal Temperature and Pressure)

Nm3 (0°C, 101.3250 kPa)

GPA adopted 15°C, 101.3250 kPa (abs) as standard conditions for SI units. Thus standard molar volumes are:

23.645 std m3/kmol at 15°C (288.15 K), 101.3250 kPa. GPA SI standard conditions.

379.49 std ft3/lb mol at 60°F (519.67°R), 14.696 psia

Other standard conditions sometimes used are:

101.325 kPa 20 °C
100.0 kPa 15 °C
14.73 psia 60 °F
14.40 psia 60 °F

Normal conditions refers to gas volumes measured at 0°C and 101.325 kPa (760 mm Hg), often abbreviated to NTP (Normal Temperature and Pressure).

The normal molar volume is: 22.414 Nm3/kmol at 0°C (273.15 K), 101.3250 kPa