Bar to PSI Converter
Convert bar to pounds per square inch (bar to psi) for metric gauges and specs
1 bar = 14.50377 psi. To convert bar to psi, multiply the bar value by 14.50377, so 2.5 bar is 36.26 psi.
How to convert bar to psi
The bar is defined as exactly 100,000 pascals. The psi is one pound-force (4.4482216 N) acting on one square inch (0.00064516 m²), which works out to 6,894.7573 Pa. Dividing 100,000 by 6,894.7573 gives the factor 14.503774, so every bar holds a little under 14.5 psi. If your number started life in psi, the psi to bar converter runs the reverse, and the pressure converter lists bar alongside kPa, MPa, atm and mmHg.
Because the bar is metric and the psi is imperial, the factor is never a round number, and rounding too early is the usual source of error. Carry 14.504 through multi-step calculations; 14.5 is fine for a single reading. Metric spec sheets in kilopascals pair with the psi to kPa converter.
Step by step
- Take the pressure in bar (or convert millibar by dividing by 1,000).
- Multiply it by 14.50377.
- Round to one decimal for tires, to the nearest psi for high pressures.
- Check whether the source was gauge (barg) or absolute (bara).
See it on a scale
Worked examples
A European car tire placard, espresso brewing pressure and a standard scuba cylinder fill.
2.4 bar ÷ 0.0689475729 = 34.809057 psi
= 34.809057 psi
9 bar ÷ 0.0689475729 = 130.53396 psi
= 130.53396 psi
200 bar ÷ 0.0689475729 = 2,900.7548 psi
= 2,900.7548 psi
Is bar an SI unit?
No. The bar is a metric unit but not an SI unit: it is defined as exactly 100,000 pascals, and the pascal, one newton per square meter, is the SI unit of pressure.
The bar survives because its size is so convenient. One bar is within 1.3% of sea-level air pressure, so a reading in bar tells you roughly how many atmospheres you have. Formal SI documents, including the BIPM SI Brochure, express pressure in pascals and their multiples, while industry keeps the bar for tires, boilers, dive cylinders and hydraulics.
Because it is exactly 10⁵ Pa, the bar sits on a clean decimal ladder with SI units, and only the step into US units is awkward:
- 1 bar = 100 kPa = 0.1 MPa
- 1 mbar = 1 hPa = 100 Pa
- 1 bar = 14.5038 psi, with no round relationship
A pascal is a newton per square meter, so pressure questions often lead back to force; the force converter covers newtons, pounds-force and kilogram-force.
How many psi is 1 bar of boost?
One bar of turbo boost equals 14.5 psi of boost, because both gauges read pressure above the surrounding air and the ordinary factor of 14.5038 applies. A European spec quoting 1.2 bar of boost matches about 17.4 psi on a US gauge.
The catch is the reference. At sea level, 1 bar of boost means the intake manifold holds about 2.01 bar absolute, or 29.2 psia. Engine sensors and tuning software often log that absolute figure, so a datalog can show roughly 2 bar where the dashboard gauge shows 1 bar.
| Boost (bar) | Boost (psi) | Absolute at sea level |
|---|---|---|
| 0.5 bar | 7.3 psi | 1.51 bara (21.9 psia) |
| 0.8 bar | 11.6 psi | 1.81 bara (26.3 psia) |
| 1 bar | 14.5 psi | 2.01 bara (29.2 psia) |
| 1.5 bar | 21.8 psi | 2.51 bara (36.5 psia) |
| 2 bar | 29 psi | 3.01 bara (43.7 psia) |
At altitude the surrounding air pressure is lower, so the same absolute manifold pressure shows up as more boost on the gauge.
Bar to psi conversion chart
The chart runs in 0.1 bar steps through the tire range, then covers espresso, compressor, washer and dive-cylinder pressures. Values are rounded to two decimals.
| Bar (bar) | PSI (psi) |
|---|---|
| 0.1 bar | 1.45 psi |
| 0.5 bar | 7.25 psi |
| 1 bar | 14.5 psi |
| 1.5 bar | 21.76 psi |
| 1.8 bar | 26.11 psi |
| 2 bar | 29.01 psi |
| 2.1 bar | 30.46 psi |
| 2.2 bar | 31.91 psi |
| 2.3 bar | 33.36 psi |
| 2.4 bar | 34.81 psi |
| 2.5 bar | 36.26 psi |
| 2.6 bar | 37.71 psi |
| 2.8 bar | 40.61 psi |
| 3 bar | 43.51 psi |
| 3.5 bar | 50.76 psi |
| 4 bar | 58.02 psi |
| 5 bar | 72.52 psi |
| 6 bar | 87.02 psi |
| 7 bar | 101.53 psi |
| 8 bar | 116.03 psi |
| 9 bar | 130.53 psi |
| 10 bar | 145.04 psi |
| 12 bar | 174.05 psi |
| 15 bar | 217.56 psi |
| 20 bar | 290.08 psi |
| 50 bar | 725.19 psi |
| 100 bar | 1,450.38 psi |
| 150 bar | 2,175.57 psi |
| 200 bar | 2,900.75 psi |
| 232 bar | 3,364.88 psi |
| 250 bar | 3,625.94 psi |
| 300 bar | 4,351.13 psi |
Bar vs psi: how do the two units compare?
The bar is the larger unit and a clean step of the SI pascal; the psi is a smaller US customary unit with an awkward link to the pascal.
| Attribute | Bar | PSI |
|---|---|---|
| Symbol | bar | psi |
| System | Metric (non-SI) | Imperial / US |
| Defined as | 100,000 Pa | 6,894.757 Pa |
| One unit equals | 14.503774 psi | 0.068947573 bar |
| Closest everyday anchor | One standard atmosphere (1 bar = 0.98692 atm) | About 6.8% of one atmosphere |
| Common multiples | Millibar (= 1 hPa) for weather; kilobar in geology | ksi (1,000 psi) for material strength |
| Espresso brewing pressure (typical) | 9 bar | 130.5 psi |
| Scuba cylinder fill (typical) | 200 or 232 bar in Europe | 3,000 psi for a US aluminum 80 |
5 key differences
- Multiplying by 14.504 takes bar to psi, so the psi figure is always the bigger number for the same pressure.
- The bar steps through the SI by powers of ten (1 bar = 100 kPa = 0.1 MPa), while the psi has no decimal link to the pascal.
- One bar is 0.987 standard atmospheres, whereas 1 psi is only 0.068 atm, which is why bar readings feel like atmospheres and psi readings do not.
- Weather maps use the millibar, one thousandth of a bar, which is 0.0145 psi.
- A 200 bar dive fill equals 2,900.8 psi, just under the 3,000 psi service pressure of a US aluminum 80 cylinder.
Metric pressure ratings you will see in bar
Common products and systems specified in bar, converted to psi. Ranges are typical, not specifications; your equipment's manual has the real figure.
| Where you see it | Bar | PSI |
|---|---|---|
| European car tire placard | 2.2–2.6 bar | 31.9–37.7 psi |
| Sealed central-heating boiler (cold) | 1–1.5 bar | 14.5–21.8 psi |
| Espresso brewing pressure | 9 bar | 130.5 psi |
| Espresso pump rating (maximum) | 15 bar | 217.6 psi |
| Home pressure washer (EU rating) | 110–150 bar | 1,595.4–2,175.6 psi |
| Mobile hydraulics (excavators, presses) | 200–350 bar | 2,900.8–5,076.3 psi |
| Hookless bike rim limit | 5 bar | 72.5 psi |
What is a bar?
A bar is a metric unit of pressure equal to exactly 100,000 pascals (100 kPa), slightly less than one standard atmosphere of 101,325 Pa. It takes its name from the Greek baros, meaning weight, and its clean relationship to the pascal made it the everyday pressure unit across Europe and much of the world for tires, boilers, diving and industry.
Its small sibling, the millibar, is identical to the hectopascal (1 mbar = 1 hPa = 100 Pa), which is why weather charts in Europe and aviation reports can switch between the two with no conversion. The mean sea-level pressure of 1,013.25 hPa is 1,013.25 mbar, or 1.01325 bar.
Why so many metric specs use bar instead of kPa
Bar values stay short: 2.4 bar is easier to print on a tire placard than 240 kPa, and 200 bar reads better on a cylinder than 20 MPa. Canada and Australia prefer kPa on tire placards, while most of Europe uses bar.
Scuba cylinder pressures: bar to psi
Dive cylinders are filled in bar in most of the world and in psi in the United States. These are gauge pressures at the cylinder valve.
| Bar | PSI | What it means |
|---|---|---|
| 50 bar | 725 psi | Common reserve or turn pressure |
| 100 bar | 1,450 psi | Half of a 200 bar fill |
| 200 bar | 2,901 psi | Standard steel or aluminum fill (Europe) |
| 206.8 bar | 3,000 psi | Aluminum 80 rating (3,000 psi) |
| 232 bar | 3,365 psi | High-pressure DIN fill |
| 300 bar | 4,351 psi | 300 bar steel cylinder |
What is the difference between barg and bara?
Barg is gauge pressure, read above the local atmosphere, and bara is absolute pressure, read from a perfect vacuum, so at sea level bara is roughly barg plus 1.01325. Process and industrial specs add the suffix to remove any doubt, and a US gauge shows the gauge version as psig. Converting between the two references needs the atmosphere, about 1.01325 bar or 14.696 psi at sea level.
Example: a compressed-air line specified at 10 bara reads 10 − 1.01325 = 8.98675 barg on a gauge, which is 130.3 psig. A careless straight conversion would give 145 psi and overstate the gauge reading by almost 15 psi.
Boiler gauges are a good everyday case. A sealed home heating system that shows 1.5 bar is 1.5 bar above atmospheric pressure. If you see it quoted as 21.8 psi on a US forum, it is the same gauge value, not a different system.
How do you convert bar to psi in your head?
Multiply the bar value by 14.5, which is within 0.03% of the exact factor: 2.4 bar × 14.5 = 34.8 psi against the exact 34.81 psi. For a rough figure, multiply by 15 and take off 3%: 200 bar × 15 = 3,000, minus 90 = 2,910 psi, close to the exact 2,901 psi.
- Do not multiply by 14.7. That is psi per standard atmosphere. It overstates every result by about 1.3%, so 200 bar would come out as 2,940 psi instead of 2,901.
- Watch for kg/cm². Older Asian and European gauges use kilogram-force per square centimeter, which is 0.980665 bar, not 1 bar.
- Temperature drift. A 200 bar fill made warm will read lower once the cylinder cools, so fill pressure and settled pressure differ.
If your spec also lists a volume in liters, such as a 12 L cylinder, the liters to gallons converter gives the US equivalent. For the full set of units, open the pressure converter.
Sources and further reading
The standards and references behind the numbers on this page. Links open in a new tab.
Standards and official sources
Bar to psi FAQs
Short, exact answers to what people ask most.
How many psi is 1 bar?
1 bar equals 14.503774 psi, which most people round to 14.5 psi.
What is 2.5 bar in psi?
2.5 bar is 36.26 psi, or about 36 psi. It is a common front-tire placard value on European cars.
What is 9 bar in psi for espresso?
9 bar is 130.5 psi. That is the brewing pressure most espresso machines aim for at the coffee puck, even if the pump is rated at 15 bar (217.6 psi).
How many psi is 200 bar?
200 bar equals 2,900.8 psi, about 2,900 psi. It is the standard fill pressure for many scuba cylinders outside the US.
Is 1 bar equal to 1 atmosphere?
Almost. One standard atmosphere is 1.01325 bar, so 1 bar is about 0.987 atm. The difference is 1.3%, which matters for precise work but rarely for tires.
Why does my tire show both bar and psi?
Tires and pumps are sold worldwide, so manufacturers print both scales. The numbers describe the same gauge pressure; 2.2 bar and 32 psi are effectively the same inflation.
What is 3 bar in psi?
3 bar equals 43.51 psi. It is a common pressure-relief valve setting on sealed home heating boilers in Europe.
How many psi is 10 bar?
10 bar is 145.04 psi. Many European workshop air compressors are rated at 8 to 10 bar, which is 116 to 145 psi.
How do I convert millibar to psi?
Divide millibar by 1,000 to get bar, then multiply by 14.5038. The standard atmosphere of 1,013.25 mbar, for example, is 14.696 psi.
Related conversions
Factors from the BIPM SI Brochure (9th ed.) for the pascal and NIST SP 811 (2008) for the bar (exactly 10⁵ Pa), the psi and the standard atmosphere (101,325 Pa); the pound-force follows the 1959 International Yard and Pound Agreement. Last updated . How we verify our numbers.