Convert psi to bar pounds per square inch ↔ bars Free Online Secure
Type a value in pounds per square inch and read it in bars at once. The factor is exact by definition, the arithmetic happens in your browser, and nothing is sent anywhere.
Nothing uploaded
Common values — Convert psi to bar (pounds per square inch ↔ bars)
| psi | bar |
|---|---|
| 1 | 0.0689475729317 |
| 2 | 0.137895145863 |
| 3 | 0.206842718795 |
| 5 | 0.344737864658 |
| 10 | 0.689475729317 |
| 20 | 1.37895145863 |
| 50 | 3.44737864658 |
| 100 | 6.89475729317 |
Where these units come from
Pressure is force spread over an area, and the SI unit says so plainly: a pascal is one newton on one square metre. It is a very small amount — ordinary air presses on us with about 101,325 of them — so practical work uses multiples. The bar was invented in the 1900s by the meteorologist Vilhelm Bjerknes as a round 100,000 pascals, close enough to sea-level air pressure to be a convenient yardstick, and it stuck in weather, in diving and in tyre gauges across Europe. The pound per square inch came the other way, straight from the pound and the inch, and it still rules American industry and the garage forecourt.
Where you meet them
Tyres are the place most people meet pressure, quoted in bar in Europe and in psi in the United States and Britain. Beyond that: weather maps in hectopascals, which are the same number as millibars; boilers, hydraulics and compressed air in bar; gas cylinders, hoses and engine testing in psi; and vacuum work in pascals, where the small unit is finally the right size.
Questions people ask
Is tyre pressure measured from zero or from the air around it?
From the air around it. A gauge reads gauge pressure — the amount above the surrounding atmosphere — so a tyre at 2.2 bar actually holds about 3.2 bar of absolute pressure. This page converts the numbers as given, without assuming one or the other, so a gauge reading in one unit converts to a gauge reading in the next.
How is a bar related to atmospheric pressure?
A bar is exactly 100,000 pascals, which is close to the atmosphere but not equal to it: standard atmospheric pressure is 1.01325 bar. Under water the pressure rises by roughly one bar for every ten metres of depth, so a diver at 30 metres feels about four bar in total, counting the air above.
Is the answer exact?
Where both units are defined in terms of one another by whole numbers, yes — the page says so above the figure, and the only rounding is in how many digits are shown. Where the ratio has no finite decimal, the page shows twelve significant digits and says the relation is approximate rather than pretending otherwise.
Does anything I type leave my device?
No. The arithmetic runs in your browser; nothing is uploaded and there is no server to upload it to. Load the page once and it keeps working with the network switched off.
Psi to bar under the bonnet: American cars read in European units
American car manuals, tyre placards, service bulletins and boost gauges all speak in psi. Anyone elsewhere who works with those figures, on an imported car or on a project that follows an American guide, must turn them into bar before they mean anything on a local gauge. To convert psi to bar, multiply by 0.06895. A placard value of 32 psi is 2.2 bar, 15 psi of turbo boost is 1.03 bar and 200 psi of compression is 13.8 bar. The calculator above multiplies while you type, and the sections below walk through a vehicle from the tyres to the engine.
Below there are worked examples, a profile of each unit, a comparison, many cases from automotive practice and the usual slips. Everything is computed in your browser and nothing is uploaded. For safety, respect the pressures printed on the vehicle.
How to convert psi to bar: multiply by 0.06895
The rule
One psi is 6,894.757 pascals and one bar is 100,000 pascals, so one psi equals 0.06894757 bar, usually rounded to 0.06895. To convert psi to bar, multiply the psi figure by that factor. 30 psi gives 2.07 bar, 90 psi gives 6.2 bar and 5,000 psi gives 344.7 bar. To go back, multiply bar by 14.5038.
Worked examples
A placard value of 35 psi is 2.41 bar. A truck tyre at 110 psi is 7.6 bar. A radiator cap rated at 16 psi is 1.1 bar, and a hydraulic jack at 10,000 psi works at 689.5 bar.
How exact it is
The factor carries no hidden rounding, since it rests on two exact definitions. For everyday use 0.069 is enough, with an error under 0.1 per cent.
A quick sanity test
The answer in bar is nearly fifteen times smaller than the number of psi. If a “convert psi to bar” calculation gave a larger number than you started with, you used the factor from the other direction.
Psi
The unit of American gauges
Psi is short for pound-force per square inch. It is the unit on American tyre placards, service manuals and workshop gauges. Many gauges also carry a second scale in kPa or bar.
Where it appears
Tyre placards, service manuals, boost gauges and workshop equipment in the United States.
The bar
The practical metric unit
The bar equals 100,000 pascals and is close to atmospheric pressure at sea level. European gauges, tyre labels and service documents use it, and so do most compressors and cylinders outside North America.
Where it appears
Tyres, boost gauges, fuel systems, compressors and industrial equipment.
Psi or bar?
A psi is worth 0.069 bar, so the number in bar is almost fifteen times smaller. 100 psi equals 6.9 bar, and 1,000 psi equals 68.9 bar. The two units describe the same pressure and differ only in scale.
The conversion is exact, with no hidden rounding. The trap is the direction: from psi to bar the figure drops.
Where the conversion shows up
Tyres on American cars
A placard on the door pillar reads 32 psi, 2.2 bar, or 35 psi, 2.4 bar. Light-truck tyres need 65 psi, 4.5 bar, and heavy-truck tyres 100 to 120 psi, 6.9 to 8.3 bar. A “convert psi to bar” calculation is the first step in setting any of them correctly with a European pump.
Engine and fuel system
Oil pressure runs at 10 psi at idle and 40 to 60 psi at speed, which is 0.7 and 2.8 to 4.1 bar. Port fuel injection operates at 40 to 60 psi, 2.8 to 4.1 bar, and direct injection at 2,000 to 3,000 psi, 138 to 207 bar.
Turbocharger boost
Boost gauges in American cars show psi above atmospheric. A mild 8 psi is 0.55 bar, a sporty 15 psi is 1.03 bar and a racing 30 psi is 2.07 bar. The absolute pressure in the intake is higher by one atmosphere.
The sidewall number
The pressure printed on a tyre sidewall is the maximum the tyre can safely hold, for instance 44 psi, 3.0 bar, for a passenger tyre or 80 psi, 5.5 bar, for a light-truck tyre. It is not the pressure to use. The recommended value is on the vehicle placard, usually much lower.
Recreational vehicles
The tyres of a motorhome often need 70 to 80 psi, 4.8 to 5.5 bar, to carry the load, while a trailer may need 35 to 65 psi, 2.4 to 4.5 bar. An ATV runs on only 5 to 7 psi, 0.34 to 0.48 bar. A low-pressure gauge is needed for the last.
Bicycle tyres in psi
Road tyres say "MAX 120 PSI", which is 8.3 bar, city tyres "35 to 65 PSI", 2.4 to 4.5 bar, and mountain tyres run at 25 to 35 psi, 1.7 to 2.4 bar. The sidewall gives limits; the pressure to use depends on the rider's weight and the surface.
Motorcycles
A motorcycle typically runs at 28 to 42 psi, 1.9 to 2.9 bar, and the front and rear values differ. American manuals list them as "front/rear" in psi, so a conversion of both is needed. A difference of 2 psi, 0.14 bar, is noticeable in handling.
The mental shortcut
To convert psi to bar in your head, divide by 15 and add 3 per cent. For 100 psi: 6.67 plus 0.2 gives 6.87, against 6.89. For 3,000 psi: 200 plus 6 gives 206, against 206.8. The method is good for rapid estimates.
Spreadsheet formulas
To convert psi to bar in a spreadsheet, put the pressures in psi in column A and type =A2*0.0689476 in column B. For the reverse, =B2/0.0689476. A third column with =A2*6.894757 gives kPa for cross-checking.
Rounding and precision
American gauges are often divided in steps of 2 psi, about 0.14 bar. When you convert psi to bar from such a gauge, one decimal is enough: 87 psi is 6.0 bar. Writing 5.99854 would suggest an accuracy the dial does not have.
Landmarks to memorise
10 psi is 0.69 bar. 14.5 psi is 1 bar. 30 psi is 2.07 bar. 50 psi is 3.45 bar. 100 psi is 6.9 bar. 145 psi is 10 bar. 1,000 psi is 69 bar. To convert psi to bar by eye, scale from these values.
Reference ladder
20 psi is 1.379 bar. 35 psi is 2.413 bar. 45 psi is 3.103 bar. 60 psi is 4.137 bar. 80 psi is 5.516 bar. 120 psi is 8.274 bar. 200 psi is 13.79 bar. 300 psi is 20.68 bar. 1,500 psi is 103.4 bar. A ladder like this speeds up checks.
Checking by reversing
To check a “convert psi to bar” calculation result, multiply the answer by 14.5038. If 100 psi became 6.895 bar, then 6.895 times 14.5038 returns 100. A second test is size: the bar figure should be about fifteen times smaller.
Link to kPa and atmospheres
One psi is 6.895 kPa, 0.068 atmospheres and 51.7 mmHg. A pressure of 100 psi is 689.5 kPa, 6.8 atmospheres and 6.9 bar. American gauges often print kPa as a second scale.
Monitoring systems
American tyre-pressure monitoring systems must warn when any tyre is 25 per cent under the placard value. For a 35 psi placard, the warning comes at 26 psi, which is 1.8 bar. Dashboards can often be switched between psi and bar, which helps owners of imported cars.
A worked example
A pressure washer sold in the United States has a label of "1,800 psi, 1.5 GPM". The pressure is 1,800 × 0.06895 = 124.1 bar. The flow of 1.5 gallons a minute is 5.7 litres a minute. The unit is therefore weaker than the usual European machine of 150 bar.
Gauge and absolute pressure
A tyre gauge shows gauge pressure, written psig. The absolute pressure, psia, is higher by 14.7 psi. A reading of 100 psig is 114.7 psia, which is 6.9 bar gauge and 7.9 bar absolute. The distinction matters in gas-law calculations.
Altitude
The atmosphere presses with 14.696 psi at sea level, 1.01325 bar. At 1,500 metres it presses with 12.2 psi, 0.84 bar, and on Everest with 4.8 psi, 0.33 bar. Aircraft altimeters in America use inches of mercury, 29.92 at sea level.
Aircraft cabins
A cabin is held at about 11 psi, 0.75 bar, equivalent to 2,400 metres. A spacesuit works at 4.3 psi, 0.3 bar, of pure oxygen. These are among the lowest pressures human beings live with.
Gas pipelines in the home
Gas is supplied to American houses at 0.25 psi, 17 millibar, about 7 inches of water. A burner marked 0.5 psi therefore accepts about 34 millibar. European house installations work at 20 to 30 millibar, so the two systems are close.
Boilers and steam
A home boiler works at 12 to 15 psi, 0.8 to 1.0 bar, with a relief valve at 30 psi, 2.07 bar. Steam locomotives ran at 200 to 250 psi, 13.8 to 17.2 bar. Old documents give the values in psi.
Pressure sensors
American sensors are sold as 0 to 100 psi, 0 to 6.9 bar, 0 to 300 psi, 0 to 20.7 bar, and 0 to 1,000 psi, 0 to 68.9 bar. When replacing one, pick the nearest European range: 0 to 7, 0 to 25 or 0 to 70 bar.
Paintball and air rifles
Paintball bottles hold 3,000 or 4,500 psi, 207 or 310 bar. Pre-charged air rifles are filled to 2,000 to 3,000 psi, 138 to 207 bar. A station set in bar must be stopped at 207 and not 300 for a 3,000 psi bottle. This is a point where a “convert psi to bar” calculation prevents real danger.
Fire extinguishers
A dry-chemical extinguisher label reads about 195 psi, 13.4 bar. If the gauge needle sits outside its green band, the extinguisher is not ready. The band is printed in psi on American models and in bar on European ones.
Drinks dispensing
Beer dispensing systems use 10 to 14 psi, 0.7 to 1.0 bar, and soft-drink systems 70 to 90 psi, 4.8 to 6.2 bar. A CO₂ cylinder holds 800 to 1,000 psi, 55 to 69 bar, at room temperature.
Temperature and pressure
Pressure changes about 1 psi for every 10 °F, so roughly 0.07 bar for every 5.5 °C. A tyre set to 32 psi at 70 °F reads 28 psi at 30 °F, which is 1.93 bar instead of 2.2 bar. Check the tyres each time the season changes.
A check by pascals
To confirm a “convert psi to bar” calculation result, go through pascals: psi × 6,894.757 / 100,000. For 100 psi this gives 6.895 bar. If the two routes disagree, a digit has been mistyped.
Fuel pressure gauges
A gauge tee on a petrol injection rail reads 40 to 60 psi, which is 2.8 to 4.1 bar, on most port-injected engines. A reading that drops by 10 psi, 0.7 bar, after the engine is switched off suggests a leaking injector or regulator. A “convert psi to bar” calculation lets a mechanic compare the reading with a European workshop manual.
Leak-down tests
A leak-down tester feeds 100 psi, 6.9 bar, into a cylinder at top dead centre and reports the percentage that escapes. Less than 10 per cent is healthy, and more than 20 per cent calls for repair. The input pressure is fixed in psi on American testers and in bar on European ones.
Tyre inflators at petrol stations
Forecourt inflators in the United States are set in psi, and most can be preset: 35 psi means they stop at 2.41 bar. Some European machines offer both units on a button. If the unit is not clear on the display, convert the placard value first and watch the figure rise to the correct number.
Nitrogen in tyres
Some garages fill tyres with nitrogen. The dry gas changes pressure slightly less with temperature, and leaks a little more slowly, but the placard values are the same, 32 psi or 2.2 bar. Air is perfectly adequate for ordinary use.
Cooling system
A radiator cap holds the cooling system at 13 to 16 psi, 0.9 to 1.1 bar, which raises the boiling point of coolant by roughly 20 °C. A cap of the wrong rating either leaks or allows overheating. Always match the rating to the engine's design.
Air conditioning
An air-conditioning system with R134a refrigerant runs at about 25 to 45 psi, 1.7 to 3.1 bar, on the low side and 150 to 250 psi, 10 to 17 bar, on the high side, depending on the temperature. Service gauges show psi, and charts relate readings to the ambient temperature.
Compression test
A healthy petrol engine shows 150 to 200 psi, 10.3 to 13.8 bar, on a compression test. A difference of more than 10 to 15 per cent between cylinders points to a problem. American workshop manuals give the figures in psi, which a European mechanic must convert to compare.
Brakes and power steering
The hydraulic brake circuit reaches 1,000 to 2,000 psi, 69 to 138 bar, under heavy braking. A power-steering pump delivers 1,000 to 1,500 psi, 69 to 103 bar. A replacement part must be rated for these pressures in bar as well.
Hydraulic jacks and presses
A garage jack rated for 12 tons works at roughly 10,000 psi, 689 bar. A workshop press of 20 tons runs at 6,000 to 8,000 psi, 414 to 552 bar. These pressures are far above everyday ones, and gauges for them are labelled in psi or MPa.
More values for convert psi to bar
A longer list of conversions
If the value you need is not in the first list, these further conversions may be close enough to read off directly:
- 0.1 psi = 0.00689476 bar
- 0.5 psi = 0.0344738 bar
- 3 psi = 0.206843 bar
- 4 psi = 0.27579 bar
- 7 psi = 0.482633 bar
- 15 psi = 1.03421 bar
- 20 psi = 1.37895 bar
- 75 psi = 5.17107 bar
- 200 psi = 13.7895 bar
- 500 psi = 34.4738 bar
- 2,000 psi = 137.895 bar
- 10,000 psi = 689.476 bar
Common slips with a “convert psi to bar” calculation
Multiplying by 14.5038
From psi to bar the number falls. If 100 psi became 1,450, you used the factor for the other direction.
Reading the wrong dial
A dual gauge may be misread. Check which unit labels the scale you are reading before converting.
Gauge or absolute
An ordinary gauge shows gauge pressure. Do not add 14.7 psi or 1 bar unless the specification asks for absolute pressure.
Questions in brief
What is the formula to convert psi to bar?
Bar equals psi times 0.06895.
What is 100 psi in bar?
6.895 bar.
What is 3,000 psi in bar?
206.8 bar.
What is one bar in psi?
14.5038 psi.
Is the input uploaded?
No, everything is computed in your browser.
Related pages and a summary
You may also want Convert psi to kPa, Convert Pa to bar, Convert bar to Pa, Convert km to mi, Convert mi to km, Convert °C to °F, Convert °F to °C, Convert km to nmi, Convert m³ to cm³. For the opposite direction, see Convert bar to psi.
Summing up: psi become bar when multiplied by 0.06895, and the unit stays beside the figure. Everything remains in your browser, with no account and no upload.