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PSI to Bar

1 PSI (psi) = 0.0689476 Bar (bar)

Result
0.0689476 bar
1 psi = 0.0689476 bar

How Many Bar in a PSI?

One PSI (pound per square inch) equals approximately 0.0689476 bar. To convert PSI to bar, multiply the PSI value by 0.0689476, or divide by 14.5038. This conversion is one of the most frequently needed in automotive, industrial, and HVAC contexts. In the United States, tire pressure is measured in PSI — a typical passenger car tire runs at 32-35 PSI. In Europe and much of the world, the same pressure would be expressed as 2.2-2.4 bar. If you are inflating tires at a gas station abroad, renting a car in Europe, working with industrial pneumatic equipment, or reading specifications for pressure washers, compressors, or hydraulic systems, you will encounter PSI-to-bar conversions regularly. Scuba divers also use both units: US dive computers often display PSI while European models show bar, with a full aluminum tank holding about 3,000 PSI (207 bar).

How to Convert PSI to Bar

  1. Start with your pressure value in PSI.
  2. Multiply the PSI value by 0.0689476 to get bar.
  3. For example, 35 PSI x 0.0689476 = 2.413 bar.
  4. For a quick mental estimate, divide PSI by 14.5 or by 15 for rough calculations.
  5. Another shortcut: 1 bar is approximately 14.5 PSI, so 30 PSI is about 2 bar and 45 PSI is about 3 bar.

Real-World Examples

Your car tire sticker says 35 PSI. You are at a European gas station that shows bar.
35 x 0.0689476 = 2.41 bar. Set the air pump to 2.4 bar.
A scuba tank is filled to 3,000 PSI. What is that in bar?
3,000 x 0.0689476 = 206.8 bar. A standard aluminum 80 tank is rated for 207 bar.
An espresso machine requires 9 bar of pressure. Is your 130 PSI supply sufficient?
130 x 0.0689476 = 8.96 bar. Marginally insufficient — you need slightly more than 130 PSI for consistent 9 bar extraction.
A hydraulic system operates at 5,000 PSI. What is the operating pressure in bar?
5,000 x 0.0689476 = 344.7 bar. This is common for heavy construction equipment like excavators.
A bicycle tire recommends 100 PSI for road riding. What is that in bar?
100 x 0.0689476 = 6.89 bar. Road bike tires typically run between 6-8 bar (87-116 PSI).

Quick Reference

PSI (psi) Bar (bar)
1 0.0689476
2 0.137895
5 0.344738
10 0.689476
25 1.72369
50 3.44738
100 6.89476
500 34.4738
1,000 68.9476

History of PSI and Bar

PSI (pounds per square inch) is an imperial unit that emerged naturally from the British engineering tradition of measuring force in pounds and dimensions in inches. It became the dominant pressure unit in American industry during the Industrial Revolution. The bar was introduced by British meteorologist Napier Shaw in 1909 as a convenient metric unit for atmospheric pressure — one bar (100,000 pascals) is very close to one standard atmosphere (101,325 pascals). The bar is not an official SI unit (the pascal is), but it was adopted widely in European industry because it provides conveniently sized numbers for everyday pressures. Tire pressure in bar typically falls between 2-4 for cars, while PSI values range from 30-60 — both are easy-to-work-with numbers. The International Bureau of Weights and Measures technically discourages bar usage in favor of the pascal or kilopascal, but bar remains firmly established in European industrial practice, weather reporting, and everyday use.

Common Mistakes to Avoid

  • Confusing bar with atmosphere (atm). One bar = 100,000 Pa, while one atmosphere = 101,325 Pa. They are close (1 atm = 1.01325 bar) but not identical. For tire pressure and industrial applications, the difference is usually negligible, but in scientific work it matters.
  • Using the wrong conversion direction. To convert PSI to bar, multiply by about 0.069 (the number gets smaller). If your bar result is larger than the PSI input, you went the wrong way.
  • Confusing "gauge pressure" (PSIG) with "absolute pressure" (PSIA). Gauge pressure reads zero at atmospheric pressure, while absolute pressure includes atmospheric pressure. A tire at 35 PSIG is actually at about 49.7 PSIA (35 + 14.7). Most everyday pressure readings are gauge pressure.

Frequently Asked Questions

What is a good tire pressure in both PSI and bar?
Most passenger car tires: 30-35 PSI (2.1-2.4 bar). SUVs and trucks: 35-45 PSI (2.4-3.1 bar). Performance/sports cars: 32-40 PSI (2.2-2.8 bar). Road bicycles: 80-130 PSI (5.5-9.0 bar). Mountain bikes: 25-35 PSI (1.7-2.4 bar). Always check the sticker on your driver's door jamb for the manufacturer's recommendation.
What is the difference between bar and millibar?
One bar = 1,000 millibar (mbar). Millibar is commonly used in meteorology for barometric pressure. Standard atmospheric pressure is 1013.25 mbar (1.01325 bar). Weather forecasts typically report pressure in millibars or hectopascals (hPa), which are numerically identical (1 mbar = 1 hPa).
Why does the US use PSI while Europe uses bar?
The US uses PSI because it developed from the imperial measurement tradition of pounds and inches. Europe adopted bar as part of metric-aligned standardization. Both are "engineering" units rather than pure SI (which prefers pascals). The persistence of PSI in the US mirrors the broader American retention of imperial units.
At what PSI/bar should I inflate my tires in cold weather?
Tire pressure drops about 1 PSI (0.07 bar) for every 10 degrees Fahrenheit (5.5 degrees Celsius) of temperature decrease. If your tires are rated at 35 PSI and the temperature drops 30 degrees F from when you last inflated, your tires may be at 32 PSI. Check pressure when tires are cold (before driving) and inflate to the manufacturer spec.
Quick Tip

A handy rule of thumb: 15 PSI is approximately 1 bar. So 30 PSI is about 2 bar, 45 PSI is about 3 bar, and so on. This "divide by 15" shortcut overestimates by about 3%, which is close enough for setting tire pressure at a gas station.