Difference between Standard and Normal Conditions


Standard conditions commonly refers to gas volumes measured at:

15°C and 101.3250 kPa

60°F and 14.696 psia

These P & T conditions are often indicated as Standard Tem- perature 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. 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.


Normal conditions refers to gas volumes measured at 0°C and 101.3250 kPa (760 mm Hg), often abbreviated to NTP (Normal Temperature and Pressure). The normal molar vol- ume is:

22.414 Nm3/kmol at 0°C (273.15 K), 101.3250 kPa