Pressure Converter — bar, psi, kPa, atm & more

How it works

Pressure is force spread over an area, and every unit is a fixed multiple of the SI unit, the pascal (one newton per square metre). Per NIST SP 811:

• 1 bar = 100,000 Pa (exactly), and 1 millibar = 100 Pa, so weather millibars are just hectopascals.
• 1 standard atmosphere = 101,325 Pa (exactly) = 1.01325 bar.
• 1 psi = 6,894.76 Pa — a pound-force spread over a square inch.
• 1 torr = 1 atm ÷ 760 ≈ 133.322 Pa, the same value as a conventional millimetre of mercury (mmHg).

The calculator converts your value to pascals and then to the unit you want, so any pairing — bar↔psi, atm↔kPa, mmHg↔bar — works the same way.

Worked example

Converting 1 bar to psi: 1 bar = 100,000 Pa, and 1 psi = 6,894.76 Pa, so 100,000 ÷ 6,894.76 = 14.5038 psi. Going the other way, 1 atmosphere = 101,325 Pa = 101.325 kPa.

Frequently asked questions

How many psi are in a bar?

About 14.5038. A bar is 100,000 pascals and a psi is 6,894.76 pascals, so dividing gives roughly 14.5 psi per bar — handy for tyre pressures.

What is the difference between bar and atmosphere?

They are close but not equal: 1 atmosphere = 101,325 Pa, while 1 bar = 100,000 Pa. So one atmosphere is about 1.013 bar — the atmosphere is defined from mercury-column physics, the bar as a round metric value.

How do I convert psi to kPa?

Multiply psi by about 6.895, since 1 psi = 6,894.76 Pa = 6.89476 kPa. For example, 32 psi (a common tyre pressure) is about 220.6 kPa.

What is a torr, and how does it relate to mmHg?

A torr is one 760th of a standard atmosphere, ≈ 133.322 Pa. The conventional millimetre of mercury is defined to the same value, so torr and mmHg are interchangeable in everyday use.

What is the SI unit of pressure?

The pascal (Pa), equal to one newton per square metre. It is small, so kilopascals (kPa) and bar are more common for tyres, weather and industry.

Are these conversions exact?

The bar (100,000 Pa) and standard atmosphere (101,325 Pa) are exact by definition; the psi follows from the exact pound-force and inch. Only the displayed result is rounded.