PSI to Bar Converter
Convert PSI to bar and vice versa. Also displays kPa, atm, and mmHg equivalents for comprehensive pressure unit conversion.
PSI to Bar Converter
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Formula: Bar = PSI x 0.0689476
Worked example โ 35 PSI = 2.4132 bar = 241.32 kPa
Formula
Bar = PSI x 0.0689476
Multiply PSI by 0.0689476 to get bar. To convert bar to PSI, divide by 0.0689476 (or multiply by 14.5038). One bar equals exactly 100,000 pascals. For kPa, multiply PSI by 6.89476. For atmospheres, divide PSI by 14.696.
Worked Examples
Example 1: Converting Tire Pressure
Problem:A tire door sticker says 35 PSI. What is this in bar?
Solution:bar = PSI x 0.0689476 bar = 35 x 0.0689476 = 2.4132 bar kPa = 35 x 6.89476 = 241.3166 kPa atm = 35 / 14.696 = 2.3816 atm
Result:35 PSI = 2.4132 bar = 241.32 kPa
Example 2: Converting Scuba Tank Pressure
Problem:A dive tank is rated at 232 bar. What is this in PSI?
Solution:PSI = bar / 0.0689476 PSI = 232 / 0.0689476 = 3364.8789 PSI kPa = 232 x 100 = 23200.0000 kPa atm = 232 / 1.01325 = 228.9539 atm
Result:232 bar = 3364.88 PSI = 23,200 kPa
Frequently Asked Questions
What is the conversion factor from PSI to bar?
One PSI equals 0.0689476 bar, and one bar equals 14.5038 PSI. This conversion is derived from the definitions: one PSI is one pound-force per square inch (6894.76 Pa), and one bar is exactly 100,000 Pa. Dividing 6894.76 by 100,000 gives 0.0689476 bar per PSI. This conversion is used extensively in automotive, industrial, and diving applications where pressure specifications cross between American and European standards.
Where is PSI used versus bar?
PSI (pounds per square inch) is the primary pressure unit in the United States, used for tire pressure, water systems, HVAC, hydraulics, and compressed air. Bar is the standard in most of Europe, Asia, and internationally, used for tire pressure, industrial systems, and scuba diving. Many modern pressure gauges display both units. Automotive tire sidewalls often show both PSI and bar (or kPa) ratings. The international trend is moving toward bar and pascal, but PSI remains dominant in American industry.
How do PSI and bar relate to atmospheric pressure?
Standard atmospheric pressure at sea level is 14.696 PSI or 1.01325 bar. This means one bar is very close to one atmosphere, which makes bar a convenient unit since many applications operate near atmospheric pressure. A car tire at 32 PSI has about 2.21 bar of gauge pressure, or 3.22 bar absolute (adding atmospheric pressure). Weather stations report atmospheric pressure in hectopascals (millibars), typically ranging from 950 to 1050 mbar as weather systems pass through.
What PSI and bar values are typical for common applications?
Car tires typically run 30-35 PSI (2.07-2.41 bar). Bicycle road tires use 80-130 PSI (5.5-9.0 bar). Home water pressure is usually 40-80 PSI (2.8-5.5 bar). Scuba tanks are filled to 3000 PSI (207 bar). Industrial hydraulic systems operate at 1500-5000 PSI (103-345 bar). Pressure washers range from 1000-4000 PSI (69-276 bar). Compressed air lines typically run at 90-120 PSI (6.2-8.3 bar). These ranges help verify that your conversions are reasonable.
How do I convert PSI to kilopascals and megapascals?
Multiply PSI by 6.89476 to get kilopascals, since one pound-force per square inch is 6,894.76 pascals. For megapascals, multiply by 0.00689476. A 100 PSI line is 689.5 kPa or 0.6895 MPa. Because one bar is exactly 100 kPa, the bar figure is simply the kilopascal figure divided by 100, which makes bar and kPa trivial to move between once the PSI conversion is done.
What is the difference between psig and psia when converting to bar?
Psig is referenced to the surrounding atmosphere and psia to a vacuum, and the conversion factor itself does not change the reference. Converting 30 psig gives 2.07 bar gauge, often written barg. To reach absolute, add local atmospheric pressure first: 30 psig is about 44.7 psia at sea level, which is 3.08 bar absolute. Mixing the two references is the single most common error in pressure conversion.
How do tyre pressure specifications translate between PSI and bar?
Multiply the PSI figure by 0.0689476. A placard reading of 32 PSI is 2.21 bar, and 36 PSI is 2.48 bar. Vehicle placards in North America use PSI while European labels use bar or kPa, and both are gauge pressures specified with the tyre cold. Because one bar is roughly 14.5 PSI, a rounding slip of 0.1 bar is about 1.5 PSI, enough to affect handling and tread wear.
Why is the bar not an SI unit even though it is metric?
The bar is defined as exactly 100,000 pascals but was never adopted into SI, which prefers the pascal with standard prefixes such as kPa and MPa. The bar persists in industry because atmospheric pressure is close to one bar, which makes gauge readings intuitive. It is accepted for use alongside SI in many fields, but formal standards and technical documentation generally require pascals.
How do I convert PSI into metres or feet of water head?
Divide the pressure in pascals by rho g for water, which is about 998 x 9.807 = 9,788 pascals per metre of column. Since 1 PSI is 6,894.76 pascals, it corresponds to roughly 0.704 metres, or 2.31 feet, of water. Pump specifications are often quoted as head in metres while gauges read PSI or bar, so this factor lets you compare a pump curve directly against a measured system pressure.
How does temperature change a PSI or bar reading in a sealed vessel?
For a fixed volume of gas, absolute pressure is proportional to absolute temperature, so warming the container raises the reading. A tyre at 32 psig, about 46.7 psia, warmed from 20 to 30 degrees Celsius, or 293 K to 303 K, gains roughly 46.7 x 10/293 = 1.6 PSI, about 0.11 bar. This is why manufacturers specify cold inflation pressures and why readings taken after driving run high.
References
Background & Theory
1 bar = 14.5037738 psi, and 1 psi = 0.0689475729 bar. The bar is exactly 100,000 pascals by definition and the psi is exactly 6,894.75729316836 pascals, so the ratio between them is fixed but non-terminating.
Conversion reference table
| Conversion | Equivalent | Exact or rounded? |
|---|---|---|
| 1 bar | 100,000 pascals | Exact by definition |
| 1 bar | 14.5037738 psi | Derived, rounded |
| 1 psi | 6,894.75729317 pascals = 0.0689475729 bar | Exact / derived |
| 1 standard atmosphere | 101,325 Pa = 1.01325 bar = 14.6959488 psi | Exact / derived |
| 1 millibar | 100 pascals = 1 hectopascal | Exact |
| 1 kilopascal | 0.145037738 psi | Derived, rounded |
A bar is deliberately close to one atmosphere but is not equal to it - it is 1.3 percent smaller - so weather and tyre figures quoted in bar and in atmospheres are not interchangeable at any useful precision. Also check whether a reading is gauge or absolute: a tyre gauge showing 2.4 bar means 2.4 bar above the surrounding air, so the absolute pressure inside is about 3.4 bar. Multiplying bar by 14.5 rather than 14.5038 is accurate to a quarter of one percent, which is well inside the tolerance of a forecourt air line.
Reviewed for accuracy by Manoj Kumar, Mathematics Educator ยท Editorial policy
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