Pressure Converter
Pressure is the amount of force applied perpendicular to a surface, divided by the area over which it acts. It explains everyday things like how much air is in your tires, as well as how deep a submarine can dive and how weather systems form. Because so many fields measure it their own way, the same pressure can be written in many different units, which is why conversion is so often needed.
All Pressure Conversions
The SI unit is the pascal (Pa), defined as one newton per square meter. The pascal is small for everyday use, so people reach for kilopascals, bars, pounds per square inch, and other units depending on their industry. Converting between them lets engineers, scientists, divers, mechanics, and weather watchers compare numbers on a common scale.
Pressure Units Explained
The pascal (Pa) is the SI unit. Common multiples are the hectopascal (hPa = 100 Pa, used in meteorology), kilopascal (kPa = 1,000 Pa), and megapascal (MPa = 1,000,000 Pa, used for material strength and high-pressure systems). The bar equals exactly 100,000 Pa, and one millibar equals one hectopascal. The torr, named after Torricelli, is defined as 1/760 of a standard atmosphere, about 133.322 Pa, and is common in vacuum and laboratory work. In imperial engineering, the pound per square inch (psi) is standard, while ksi (kilo-pound per square inch) equals 1,000 psi and is used for high-strength materials.
How to Convert Pressure Units
Convert by going through the pascal as a common base: multiply the source value by its pascal factor, then divide by the target unit's factor. Key factors: 1 kPa = 1,000 Pa; 1 MPa = 1,000,000 Pa; 1 hPa = 100 Pa; 1 bar = 100,000 Pa; 1 torr is about 133.322 Pa; 1 psi is about 6,894.757 Pa; 1 ksi = 1,000 psi, about 6,894,757 Pa. Example: convert 30 psi to kPa. First, 30 times 6,894.757 = 206,842.7 Pa, then divide by 1,000 to get about 206.84 kPa. Reversing, 200 kPa divided by 6.894757 is about 29.0 psi. For quick checks, 1 bar = 14.5038 psi and 1 psi = 0.0689476 bar.
Common Uses
- Checking and inflating vehicle and bicycle tires (psi, kPa, or bar)
- Reading weather and barometric pressure (hPa or millibars)
- Specifying hydraulic and pneumatic system ratings (bar, MPa, psi)
- Scuba diving and gas cylinder pressure (bar and psi)
- Vacuum and laboratory work (torr and pascals)
- Material strength and structural engineering (MPa and ksi)
Accuracy Tips
Always confirm whether a reading is gauge pressure (relative to the surrounding air, often marked psig or barg) or absolute pressure (psia, bara); they differ by roughly one atmosphere. Watch the prefixes: kPa, MPa, and hPa differ by factors of 1,000 and 100, so a misplaced prefix throws results off badly. The bar and atmosphere are close but not equal: 1 atm = 1.01325 bar.
Frequently Asked Questions
How many psi are in 1 bar?
1 bar equals about 14.5038 psi. Going the other way, 1 psi equals about 0.0689476 bar.
What is standard atmospheric pressure in different units?
One standard atmosphere (atm) is exactly 101,325 Pa. That equals 101.325 kPa, 1013.25 hPa (or millibars), 1.01325 bar, 760 torr, and about 14.696 psi.
How do I convert kPa to psi?
Divide the kPa value by 6.894757. For example, 100 kPa divided by 6.894757 is about 14.5 psi. To go from psi to kPa, multiply by 6.894757 instead.
Is a bar the same as an atmosphere?
No, they are close but not equal. 1 bar = 100,000 Pa exactly, while 1 standard atmosphere = 101,325 Pa. So 1 atm equals about 1.01325 bar.
What is the difference between a torr and a millimeter of mercury?
They are nearly identical. The torr is defined as exactly 1/760 of a standard atmosphere (about 133.322 Pa), while 1 mmHg is about 133.322 Pa as well, so the two are equal to within a few parts per million.