- Donna Mills
- Published 8 Sept 2026
- Last Modified 6 Nov 2026
- 5 min
Pressure Conversion Calculator
If you need to quickly convert units of pressure, why not use our handy pressure unit conversion calculator? Our calculator makes it simple to convert one unit of pressure to another, including ATM pressure units and other common measurements of pressure.
To use the pressure unit conversion calculator, simply type in an input value and select the input units box to select a pressure unit of measure. Our calculator will then instantly provide you with the values of all other types of pressure units. Give it a go below!
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. |
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Donna is a Senior SEO Specialist at RS, specialising in the creation and optimisation of industry-led content. Passionate about connecting audiences with valuable information, she develops a wide range of resources, including industry insights and engineering calculators, designed to help professionals solve real-world challenges. At the weekend you might catch her in her Volkswagen Campervan, enjoying musical theatre, reading, and spending time with family and friends.