Convert PSI to Bar
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Science
About PSI to Bar Conversions
Tire Pressure: The Most Common Use Case
One PSI equals 0.0689476 bar. The most-searched reason for this conversion is tire pressure. US tire gauges and vehicle placards show PSI. European gauges and vehicle manuals show bar. If you rent a car in Europe and the gas station air pump shows bar, you need to know what to set it to.
| PSI | Bar | Typical use |
|---|---|---|
| 14.7 | 1.01 | Standard atmospheric pressure (sea level) |
| 28 | 1.93 | Low end of bicycle tire range |
| 30 | 2.07 | Economy car, rear tires |
| 32 | 2.21 | Common passenger car recommendation |
| 35 | 2.41 | Common passenger car recommendation |
| 36 | 2.48 | SUV typical recommendation |
| 40 | 2.76 | Max for many passenger tires |
| 44 | 3.03 | Light truck / heavily loaded vehicle |
| 50 | 3.45 | Truck / commercial vehicle |
| 80 | 5.52 | Road bicycle tire |
| 100 | 6.89 | Narrow road bike tire / industrial |
| 200 | 13.79 | High-pressure industrial air line |
| 3000 | 206.8 | Full scuba tank |
Your tire placard (inside the driver's door frame) lists the recommended cold pressure in PSI. To convert, divide by 14.5. So 35 PSI / 14.5 = 2.41 bar. For a faster estimate, divide PSI by 15. That undershoots by 3%, which means you end up slightly over-inflated. Not ideal, but safer than under-inflation.
Scuba Diving: Where the Numbers Get Big
Scuba tanks are rated in PSI in the US and bar in Europe. A standard aluminum 80 tank holds 3,000 PSI (207 bar) when full. Divers track remaining air pressure throughout the dive, and dive computers may show either unit depending on the market. Turn-around pressure of 1,500 PSI is about 103 bar. Reserve pressure of 500 PSI is about 34 bar.
Industrial and Hydraulic Pressure
Manufacturing, hydraulic systems, and pressure testing use both units depending on the country. US industrial equipment specs use PSI. European machinery uses bar (or sometimes megapascals, where 1 MPa = 10 bar). A hydraulic press operating at 5,000 PSI runs at about 345 bar.
The Convenient Near-Equivalence
Standard atmospheric pressure is 14.696 PSI or 1.01325 bar. This near-coincidence means that atmospheric pressure is roughly "14.7 PSI" and "1 bar." It also means that gauge pressure readings (which subtract atmospheric pressure) have a simple relationship: PSI gauge / 14.5 gives you bar gauge. The exact factor is 14.5038, but 14.5 gets you within 0.03%.
Why Two Systems?
PSI (pounds per square inch) comes from the imperial system. Bar is a metric unit defined as exactly 100,000 pascals, introduced in 1909 by the Norwegian meteorologist Vilhelm Bjerknes. Despite being a "metric" unit, bar is not an official SI unit. The SI unit for pressure is the pascal (Pa), but bar persists in everyday use because the pascal is inconveniently small. Standard atmospheric pressure is 101,325 Pa, which is awkward to work with compared to 1.013 bar.
Quick Conversions
| Unit Name | Symbol | Per 1 PSI |
|---|---|---|
| Atmosphere | atm | 0.068046 |
| Bar | bar | 0.0689476 |
| Inch of Mercury | inHg | 2.03602 |
| Kilopascal | kPa | 6.89476 |
| Megapascal | MPa | 0.00689476 |
| Millibar | mbar | 68.9476 |
| Millimeter of Mercury | mmHg | 51.7151 |
| Pascal | Pa | 6894.76 |
| PSI | psi | 1 |
| Torr | Torr | 51.7151 |
Frequently Asked Questions
How do I convert PSI to Bar?
To convert PSI to Bar, use the conversion where 1 PSI (psi) = 0.0689476 Bar (bar). For example, 1 PSI = 0.0689476 Bar.
What are common PSI to Bar conversions?
Here are common conversions: 1 PSI = 0.0689476 Bar, 5 PSI = 0.344738 Bar, 10 PSI = 0.689476 Bar, 25 PSI = 1.72369 Bar, 50 PSI = 3.44738 Bar, 100 PSI = 6.89476 Bar.
When would I need to convert PSI to Bar?
Inflating car tires at a European gas station that displays bar. Reading industrial pressure gauges calibrated in bar from US specifications. HVAC service manuals from the US list pressures in PSI, but your gauges read bar.
How precise are the conversions?
All conversions use exact factors verified against NIST and ISO standards with up to 10 significant figures of precision. Results are calculated using IEEE 754 double-precision arithmetic, which provides approximately 15-17 significant digits. For temperature and other non-linear conversions, exact formulas are used rather than approximations.
How many Bar is 14.696 PSI? (Standard atmospheric pressure at sea level)
14.696 PSI equals 1.013 bar Bar. This is a frequently referenced value because it represents standard atmospheric pressure at sea level.