Article — Bar to PSI Converter
Bar to PSI conversion: the exact 14.5038 factor across pressure systems
1 bar = 14.5038 PSI (rounded from the exact 100000/6894.757293168). The factor comes from the SI definitions: 1 bar equals 100,000 pascals; 1 PSI equals 6,894.757 pascals; the ratio is exact and has no measurement uncertainty. To convert bar to PSI, multiply by 14.5038. To convert PSI to bar, divide by the same number (or multiply by 0.0689476). Standard tyre pressure is about 2 bar or 30 PSI; a full scuba tank is 200 bar or 2,900 PSI; a pressure cooker runs at about 1 bar gauge (15 PSI) above atmospheric.
This calculator handles the conversion bidirectionally with no rounding error beyond the precision you choose. The default is 4 decimal places, which covers everything from casual tyre-pressure reading to engineering calibration. The quick-pick buttons cover the most common pressure values: 0.5, 1, 2, 5, 10, 30, and 100 bar.
The bar to PSI formula
PSI = bar × 14.5038. The factor is exact because both units are defined in terms of the pascal, which is the SI base unit for pressure. One pascal equals one newton per square metre, where the newton is defined from kilogram, metre, and second — all of which have exact SI definitions since 2019.
0.5 bar = 7.25 PSI low-pressure pneumatic1 bar = 14.50 PSI atmospheric pressure2 bar = 29.01 PSI passenger tyre5 bar = 72.52 PSI compressed air systems10 bar = 145.04 PSI industrial pneumatics100 bar = 1450 PSI hydraulics, scubaThe mental-math shortcut is bar × 14.5 ≈ PSI. The error is under 0.03%, which is well within tyre-gauge accuracy. For tighter work, use 14.50 or 14.504. The full precision (14.50377) only matters for laboratory calibration or where you are accumulating errors across many conversions.
Bar to PSI for tyre pressure
Standard tyre pressure for passenger cars is 2.2 to 2.4 bar (32 to 35 PSI), measured cold. The exact figure for your vehicle is on a sticker inside the driver-side door jamb, in the owner's manual, or sometimes on the fuel cap cover. Front and rear pressures may differ slightly; some cars list higher pressures for fully loaded conditions.
European cars typically display in bar; US cars in PSI; UK cars often have both on the gauge. The conversion matters most when bringing a car from one market to another, or when using a tyre-inflation pump made in a different unit system than your gauge. A 2.0 bar setting on a European pump is 29 PSI; pumping to "29" on a US scale produces the same physical pressure.
Tyre pressure rises with temperature. Driving warms the tyres by 10 to 20°C, which lifts pressure by 0.2 to 0.4 bar (3 to 6 PSI) above the cold reading. If you check warm and inflate to the cold-pressure spec, you will be 5 to 10% underinflated once the tyres cool. Always check first thing in the morning, before driving more than a few hundred metres.
Bar to PSI in pressure cookers
Home pressure cookers operate at about 1 bar gauge pressure above atmospheric — roughly 15 PSI in US-style cookers. The high-pressure setting on modern electric pressure cookers (Instant Pot and similar) sits in the 0.6 to 0.7 bar gauge range, or 9 to 10 PSI, which is lower than older stovetop models.
The pressure raises the boiling point of water from 100°C to about 120°C, which is what speeds up cooking. A 1 bar increase lifts the boiling point by roughly 18°C; this is why pressure cookers cut cooking time by 50 to 70% for foods that need extended simmering. Industrial autoclaves go much higher — 2 to 3 bar — to reach 134°C for medical sterilization.
Bar to PSI for scuba diving
Scuba cylinders are rated by working pressure. The most common aluminum 80 cubic foot tank is rated at 200 bar (2,900 PSI). Steel high-pressure tanks reach 232 bar (3,400 PSI) or 300 bar (4,400 PSI). Tank gauges in Europe read in bar; US tanks read in PSI; international charter operations often display both.
- 200 bar / 2,900 PSI = standard aluminum 80 (alu80) tank, full
- 232 bar / 3,400 PSI = European steel tanks, full
- 300 bar / 4,400 PSI = high-pressure technical diving tanks
- 50 bar / 725 PSI = absolute minimum surface pressure (safety rule)
- 70 bar / 1,000 PSI = comfortable safety margin to start ascent
- 10 bar / 145 PSI = pressure increase per 10 metres of seawater depth
Depth and pressure scale linearly underwater. Every 10 metres of seawater adds 1 bar of pressure (or 0.43 PSI per foot). At 30 metres depth, ambient pressure is 4 bar absolute (3 bar gauge plus 1 atmosphere) — gases compress and tank consumption rises proportionally. This is why dive computers calculate gas-time-remaining differently at depth than at the surface.
Industrial pressure in bar vs PSI
Industrial pressure systems mix unit conventions depending on country and application. Pneumatic tools and shop air are typically specified at 6 to 7 bar (87 to 102 PSI). Hydraulic systems run much higher: 100 to 300 bar (1,450 to 4,350 PSI) is typical for excavators, presses, and forming equipment. Steam systems and refrigerant circuits cover an even wider range.
The bar was originally proposed in 1909 by Norwegian meteorologist Vilhelm Bjerknes, who wanted a metric pressure unit that produced single-digit numbers for atmospheric pressure. Standard atmospheric pressure at sea level is 1.01325 bar, which fits the design intent neatly. The unit was formally adopted at the 9th General Conference on Weights and Measures in 1948. Though the bar is technically not an SI unit, BIPM recognises it as an acceptable practical unit, and it is the dominant pressure unit in European industry and meteorology today.
Bar vs kPa, MPa, and atmospheres
Five units handle most pressure work: pascal (Pa), kilopascal (kPa), megapascal (MPa), bar, and standard atmosphere (atm). Plus PSI in US usage. The relationships are clean: 1 bar = 100 kPa = 0.1 MPa = 0.9869 atm = 14.5038 PSI.
Different industries prefer different units. Meteorology uses millibars (1 mbar = 0.001 bar = 100 Pa, where atmospheric is around 1013 mbar). Civil engineering uses kPa and MPa for concrete and soil pressure. Chemistry and physics use pascals or kilopascals. Automotive uses bar or PSI. HVAC and refrigeration use a mix of PSI and bar depending on country.
Gauge vs absolute pressure
The pressure gauge in your hand almost always reads gauge pressure — pressure relative to atmospheric. When the gauge reads zero, the actual pressure inside is one atmosphere (about 1 bar or 14.7 PSI), because the gauge subtracts atmospheric on both sides.
To convert gauge pressure to absolute, add 1 atm: 1.01325 bar or 14.696 PSI. A 200 bar scuba tank is 201 bara — for practical purposes, the 1-bar difference is negligible compared with the tank pressure. But for low-pressure calculations (vacuum work, refrigeration low side, weather measurement), the gauge/absolute distinction is critical. A "0.5 bar" vacuum reading on a gauge can mean either +0.5 barg above atmospheric or −0.5 barg below it.
The convention is to write "barg" or "PSIG" for gauge pressure, and "bara" or "PSIA" for absolute. In practice the suffix is often dropped and context is left to determine which one is meant. Engineering documents should always specify, especially for vacuum and partial-vacuum applications where the absolute pressure determines physical behaviour.
Common bar to PSI mistakes
Most bar-to-PSI errors are mental-math slips, not understanding gaps. Three patterns account for the majority of mistakes.
If your car's door sticker shows 220 kPa and your gauge reads PSI, the conversion is 220 kPa ÷ 6.895 = 32 PSI. Some people misread the sticker as 220 PSI, which would be a dangerously overinflated tyre (about 15 bar — well above the tyre's burst limit). Always double-check unit labels on the sticker before inflating, especially for cars imported from a different market.
In refrigeration and vacuum work, a gauge reading of 0 bar means atmospheric — about 1.01 bara absolute. Pulling vacuum drops the gauge reading below zero, with a maximum negative reading of approximately −1 barg (perfect vacuum). Forgetting this can produce calculation errors that double or halve the actual pressure differential the system is working with.