STP - Standard Temperature and Pressure and NTP - Normal Temperature and Pressure

A comprehensive reference tool for standard temperature and pressure conditions including STP (IUPAC and Imperial definitions), NTP, SATP, ISA, and ICAO Standard Atmosphere. Essential for comparing chemical and physical processes across different testing standards.

StandardTemperature (°C)Temperature (K)Pressure (Pa)Pressure (kPa)Pressure (bar)Pressure (psia)Molar Volume (L/mol)Notes
STP (IUPAC Current)0273.15100000100114.50423.6442Current IUPAC definition
STP (Imperial/USA)15.6288.75101325101.3251.0132514.69624.0Common in Imperial systems
STP (IUPAC Discontinued)0273.15101325101.3251.0132514.69622.4136Older IUPAC definition, still used for Nm³
NTP20293.15101325101.3251.0132514.724.0548Standard for fan testing
SATP (IUPAC)25298.15100000100114.50424.4651Standard Ambient Temperature & Pressure
ISA15288.15101325101.3251.0132514.723.8Aircraft performance reference
ICAO Standard Atmosphere15288.15101325101.3251.0132514.723.8International Civil Aviation Organization standard