The different types of pressure units
If you’re unsure as to what all the different pressure units equate to, we’ve added a handy guide of definitions of each measurement below:
Pressure Unit | Definition |
|---|---|
| Pounds per square inch (psi) | The force of one pound-force applied to an area of one square inch. |
| Pascals (Pa) | The pascal is the International System of Unit’s unit of pressure and is defined as one newton per square metre. |
| Bar | A metric unit of pressure which is equivalent to 100,000 pascals. |
| MilliBar (mbar) | A subunit of the bar which is equal to one thousandth of a bar (0.1 kPa). |
| KiloPascals (kPa) | This unit of pressure is equal to 1,000 pascals. |
| Inches of Mercury (inHg) | Inches of Mercury refers to a unit of pressure which is based on the height of a column of mercury. One inch of mercury is equivalent to 3,386.39 pascals. |
| Inches of Water (inH2O): | Like inches of mercury but instead refers to the height of a column of water. One inch of water is roughly equivalent to 248.84 pascals. |
| Millimetres of Mercury (mmHg) | Again, this unit of pressure refers to the height of a column of mercury but in millimetres instead of inches. One mmHg is equal to roughly 133.322 pascals. |
| Millimetres of Water (mmH2O) | Refers to the height of a column of water but in millimetres instead of inches. One mmH2O is equal to 9.80665 pascals. |
| Atmospheres (atm) | This unit of pressure is often used to express atmospheric pressure at sea level and is equivalent to precisely 101,325 pascals. |
| Torr | A torr is equal to 1/760 of an atmosphere and is roughly equal to 133.322 pascals. A torr is often used interchangeably with a millimetre of mercury in pressure measurements as they are approximately equal to the same amount of pascals. |
