Bar to PSI Conversion Calculator

How to Convert Bar to PSI

The conversion from bar to PSI uses a single multiplication:

PSI = bar x 14.503773773

For most practical purposes, using 14.5038 is accurate to four decimal places. For tyre pressures, rounding to two decimal places is sufficient.

To convert PSI back to bar, divide by the same factor:

bar = PSI / 14.503773773

Where the Conversion Factor Comes From

Both bar and PSI are units of pressure, meaning force per unit area. The underlying SI unit is the pascal (Pa), defined as one newton per square metre.

• 1 bar = 100,000 pascals (exactly, by definition)
• 1 PSI = 1 pound-force per square inch = 6,894.757 pascals (from the definition of the pound-force and the inch)
• Therefore: 1 bar / 6,894.757 Pa per PSI = 14.503773773 PSI

The factor 14.5038 is an approximation rounded to four decimal places. For engineering calculations requiring greater precision, use the full factor of 14.503773773022.

Tyre Pressure: Bar vs PSI

New Zealand and most of the world outside the United States uses bar for tyre pressures. American manufacturers and some tools still quote PSI. If your car manual says 2.2 bar and your gauge reads in PSI, the correct setting is approximately 31.9 PSI.

Always use the pressure stated on the vehicle's tyre placard (inside the driver's door jamb or in the owner's manual) rather than the maximum pressure printed on the tyre sidewall.

Worked Example

Convert the default input of 1 bar to PSI (matching the calculator's default output with 2 decimal places):

1. Input: 1 bar
2. Formula: PSI = 1 x 14.503773773 = 14.503773773
3. Rounded to 2 decimal places: 14.50 PSI

A second common example: 2.2 bar (a typical car tyre pressure) = 2.2 x 14.5038 = 31.91 PSI.

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Sources and method: Conversion factor derived from NIST Special Publication 811 (2008), which defines 1 pound-force per square inch = 6,894.757 Pa and 1 bar = 100,000 Pa (exact). The PSI value 14.503773773022 is the quotient 100,000 / 6,894.757.

This calculator is for informational and general conversion purposes. For safety-critical applications such as pressure vessel design, hydraulic engineering, or medical equipment, always verify conversions against the relevant standard or specification.