Pressure Units

There are many types of pressure units used depending on the country, industry and application.

For example pascals (Pa) and inches of water (inH2O) are used for defining low air pressures, in applications such as measuring air flow through ventilation ducts on HVAC or building management systems.

Also, the millibar (mbar) and inch of mercury (inHg) pressure units are units often used to express the value of barometric measurements for meteorological purposes.

All pressure units are directly proportional to each other, and pressure values can be defined using whole units with a unique name (e.g. bar or kPa), combinations of force and area units (e.g. kgf/cm² or lbs/in²) or height of a column of liquid such as (e.g. mH₂O or inHg).

Each whole pressure unit will have a value defined in pascals such as the technical atmosphere (at) or another unit defined in pascals, such as Torr with the atmosphere (atm).

Pressure units derived from force and area units will be expressed as a mass weight divided by the square of a length measurement such as pounds per square foot (psf).

Pressure units which represent the height of a liquid are useful for measuring depth and liquid level, however due to the changing density of fluids at different temperatures, they are not recommended for precise measurements.

Measurement Unit Related Terms

More pages related to measurement unit technical terms.

• at – Technical Atmosphere Pressure Unit
• atm – Standard Atmosphere Pressure Unit
• bar Pressure Unit
• cmH2O – Centimetres of Water Column at 4 deg C Pressure Unit
• cmHg – Centimetres of Mercury at 0 deg C Pressure Unit
• daPa – Dekapascal Pressure Unit
• dyn/cm² – Dyne per Square Centimetre Pressure Unit
• ftH2O – Feet of Water Column at 4 deg C Pressure Unit
• g – Acceleration due to Gravity
• g/cm² – Grams per Square Centimetre Pressure Unit
• hPa – Hectopascal Pressure Unit
• inH2O – Inches of Water Column at 4 deg C Pressure Unit
• inHg – Inches of Mercury at 0 degrees C Pressure Unit
• kg/cm² – Kilogram per Square Centimetre Pressure Unit
• kg/mm² – Kilogram per Square Millimetre Pressure Unit
• kPa – Kilopascal Pressure Unit
• ksi – Kilopounds per Square Inch Pressure Unit
• mbar – Millibar Pressure Unit
• mH2O – Metres of Water Gauge at 4 deg C Pressure Unit
• mmH2O – Millimetres of Water Column at 4 deg C Pressure Unit
• mmHg – Millimetres of Mercury at 0 deg C Pressure Unit
• MPa – Megapascal Pressure Unit
• mPa – Millipascal Pressure Unit
• mTorr – Millitorr Pressure Unit
• N/cm² – Newton per Square Centimetre Pressure Unit
• N/m2 – Newton per Square Metre Pressure Unit
• N/mm² – Newton per Square Millimetre Pressure Unit
• oz/in² – Ounce per Square Inch Pressure Unit
• Pa – Pascal Pressure Unit
• Pressure
• psf – Pounds per Square Foot Pressure Unit
• psi – Pounds per Square Inch Pressure Unit
• Specific Gravity
• Torr Pressure Unit
• tsf – Tons per Square Foot (USA, Short) Pressure Unit
• tsi – Tons per Square Inch (UK, Long) Pressure Unit
• tsi – Tons per Square Inch (USA, Short) Pressure Unit
• Water Density
• µHg – Micron of Mercury at 0 deg C Pressure Unit