Convert psi to kPa pounds per square inch ↔ kilopascals Free Online Secure
Type a value in pounds per square inch and read it in kilopascals at once. The factor is exact by definition, the arithmetic happens in your browser, and nothing is sent anywhere.
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Common values — Convert psi to kPa (pounds per square inch ↔ kilopascals)
| psi | kPa |
|---|---|
| 1 | 6.89475729317 |
| 2 | 13.7895145863 |
| 3 | 20.6842718795 |
| 5 | 34.4737864658 |
| 10 | 68.9475729317 |
| 20 | 137.895145863 |
| 50 | 344.737864658 |
| 100 | 689.475729317 |
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.
Where are kilopascals used?
In engineering, in Canadian weather reports and on the tyre placards of cars in many countries. A kilopascal is 1000 pascals, and standard atmospheric pressure is 101.325 kilopascals. A tyre pressure of 220 kilopascals is the same as 2.2 bar, which is why the two units appear side by side on car labels.
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 kilopascals: chemistry lessons, spacecraft cabins and cars on both sides of the border
A chemistry textbook may pose a gas problem in atmospheres, mmHg and psi in the same chapter, while the answer key wants kilopascals. A spacecraft engineer sees cabin pressure in psi in NASA records and in kPa in European documents. A driver who buys a car in Canada or Australia meets placards in kPa after years of psi. The step between them is one multiplication, but it has to be right. To convert psi to kPa, multiply by 6.8948: 14.7 psi is 101.35 kPa, 5 psi is 34.5 kPa and 60 psi is 413.7 kPa. The calculator above multiplies as you type, and the sections below put the figures into classrooms, cabins and engines.
The page gives the rule with worked examples, a profile of each unit, a comparison and a long series of everyday cases, followed by the common mistakes. The calculation runs in your browser and nothing you type is sent anywhere. For safety-critical equipment, use the manufacturer's own figures.
How to convert psi to kPa: multiply by 6.8948
The rule
One psi is 6,894.757 pascals, or 6.894757 kPa. To convert psi to kPa, multiply the psi value by 6.8948: 12 psi gives 82.7 kPa, 45 psi gives 310.3 kPa and 2,200 psi gives 15,168 kPa, or 15.2 MPa. To go back, multiply kPa by 0.14504.
Worked examples
A keg regulator at 12 psi is set to 82.7 kPa. The cabin of Apollo, held at 5 psi of pure oxygen, was at 34.5 kPa. A pool filter reading 20 psi is at 137.9 kPa, and a car with a placard of 35 psi needs 241.3 kPa.
Exactness
The factor comes from two exact definitions, so no rounding hides inside it. Ordinary work can use 6.9, which is accurate to within 0.1 per cent.
A quick sanity test
The kPa figure is nearly seven times the psi figure. If a “convert psi to kPa” calculation produced a smaller number than you began with, the factor went the wrong way.
Psi
The pound-force per square inch
Psi describes the pressure of a force of one pound on an area of one square inch. It survives on American gauges, in aviation and automotive manuals, and in many textbooks printed in the United States.
Where it appears
Gauges, manuals, space-programme records and American textbooks.
The kilopascal
A thousand pascals
The kilopascal is a convenient multiple of the SI pressure unit, one thousand pascals. Chemists use it for gas laws, meteorologists in Canada for atmospheric pressure, and engineers in Australia and New Zealand for tyres and hot-water systems.
Where it appears
Chemistry, weather services, tyre placards and plumbing standards outside North America.
Psi or kPa
Every psi is worth nearly 7 kPa. 30 psi is therefore 206.8 kPa and 100 psi is 689.5 kPa. The pressure is the same; only the number and the unit change.
The conversion is exact, with no hidden rounding. The one mistake to avoid is the direction: from psi to kPa the figure rises.
Where the conversion shows up
The chemistry classroom
Standard conditions use 101.325 kPa, which in psi is 14.696. A student in a US class given a gas at 25 psi must turn it into 172.4 kPa before applying a constant of 8.314 J/(mol·K). With the pressure in kPa and the volume in litres the result comes out right. A “convert psi to kPa” calculation is the opening step of such problems.
Space cabins
The International Space Station keeps sea-level pressure, 14.7 psi, 101.3 kPa. Early American capsules used pure oxygen at 5 psi, 34.5 kPa, and a modern spacesuit works at 4.3 psi, 29.6 kPa. European and American documents quote the figures in different units.
Cars from different markets
Placards on cars sold in Canada and Australia use kPa, those in the United States psi. A typical 35 psi is 241 kPa. A driver who inflates to 240 psi, mistaking kPa for psi, would burst the tyre.
Gas-law practice
Boyle's law says pressure times volume stays constant at fixed temperature. A syringe holding 60 mL at 14.7 psi compressed to 20 mL reaches 44.1 psi, or 304 kPa. Doing the work in kPa from the beginning means a single convert psi to kPa at the start and no further unit changes.
Aquariums and ponds
The pressure at the bottom of a tank 60 cm deep is 5.9 kPa, 0.85 psi, above that at the surface. Pumps for ponds work with a head of 2 to 5 psi, 14 to 34 kPa, so a metric gauge reading in kPa is directly useful to a hobbyist.
Hot-water systems
Storage water heaters have relief valves at 850 or 1,000 kPa in Australia and at 150 psi, 1,034 kPa, in North America. A thermal expansion tank is pre-charged to the system pressure, usually 40 to 60 psi, 276 to 414 kPa.
Pressure washers
A home pressure washer marked 1,800 psi gives 12.4 MPa, 124 bar. A heavy-duty model of 3,000 psi gives 20.7 MPa. Specifications in kPa would be a number with five digits, which is why makers use MPa or bar.
Medical devices
A hospital oxygen supply arrives at 50 psi, 345 kPa, at wall outlets, and a vacuum line holds about 15 inches of mercury, 51 kPa below atmospheric. Anaesthesia gauges show kPa or psi according to the country.
The mental shortcut
To convert psi to kPa in your head, multiply by 7 and subtract 1.5 per cent. For 45 psi: 315 less 4.7 is 310.3, close to the exact figure. For 80 psi: 560 less 8.4 is 551.6. Use it when you only need a rough check.
Spreadsheet formulas
Put the readings in psi in column A and type =A2*6.894757 in column B. For the reverse use =B2/6.894757. A third column with =B2/100 gives bar, a useful cross-check for European colleagues.
Rounding in practice
Most tyre gauges resolve to 1 psi, 7 kPa. Quoting 220.632 kPa for 32 psi suggests an accuracy the gauge does not have; 220 kPa is enough. When you convert psi to kPa for chemistry, keep three or four significant figures to match the data.
Landmarks to memorise
5 psi is 34 kPa. 10 psi is 69 kPa. 15 psi is 103 kPa. 30 psi is 207 kPa. 50 psi is 345 kPa. 100 psi is 689 kPa. 145 psi is 1,000 kPa. When you convert psi to kPa by eye, interpolate between these.
Reference ladder
14.7 psi is 101.4 kPa. 20 psi is 137.9 kPa. 32 psi is 220.6 kPa. 40 psi is 275.8 kPa. 60 psi is 413.7 kPa. 80 psi is 551.6 kPa. 120 psi is 827.4 kPa. 200 psi is 1,379 kPa. A ladder like this makes checks quick.
Reverse check
To verify a “convert psi to kPa” calculation result, multiply the answer by 0.14504. If 30 psi became 206.8 kPa, then 206.8 times 0.14504 returns 30. A second test is size: the kPa number should be close to seven times larger.
Altitude and aviation
Aircraft altimeters are set to the pressure at sea level. The standard value is 101.325 kPa, which pilots in America read as 29.92 inches of mercury and those in Europe as 1013 hPa. In psi the same pressure is 14.696. At the cruise altitude of an airliner the outside pressure is only about 3.3 psi, 23 kPa.
Other pressure units
One kPa is 0.01 bar, 0.00987 atmospheres and 7.5 mmHg. 220.6 kPa is 2.206 bar, 2.18 atmospheres and 32 psi. Textbooks that use atmospheres or mmHg link to kPa through the standard atmosphere, 101.325 kPa.
Worked example from a lab
A student measures a gas at 28.5 psi in a 2.0-litre flask at 295 K. In kPa the pressure is 196.5. The amount of gas is n = pV/RT = 196,500 × 0.002 / (8.314 × 295) = 0.160 mol. Had the student used psi directly, the answer would have been wrong by a factor of nearly 7.
Gauge and absolute pressure
Most gauges show pressure relative to the air around them. Absolute pressure is greater by 101.3 kPa, 14.7 psi. A reading of 220 kPa is 321 kPa absolute. Gas-law work needs the absolute value.
Tyre-fitting safety
Fitters seat a tyre bead at no more than 40 psi, 276 kPa, and then drop to the working pressure. The limit is printed on the sidewall. A garage with a gauge in kPa has to convert the 40 psi limit, or the bead could rupture under a pressure 7 times too large if kPa were mistaken for psi.
Mountain-bike air shocks
A rear air shock for a mountain bike is pumped to 150 to 300 psi, which is 1.03 to 2.07 MPa, depending on rider weight. Pumps and shock manuals use psi everywhere, while European riders keep the setting in bar, 10 to 21. A shock pump with kPa, 1,034 to 2,068, is rare.
Hose ratings
A hydraulic hose marked "working pressure 300 psi" is tested to burst at four times that value, 1,200 psi. In kPa, that is 2,068 working and 8,274 burst. The ratio 4:1 is the usual safety factor, and it is the burst figure that data sheets in other countries sometimes list by mistake.
Drip bags and infusion
A pressure bag around an intravenous fluid is inflated to 300 mmHg, which is 40 kPa or 5.8 psi, to push the fluid in quickly. Gauges on infusion equipment show mmHg, kPa or psi according to the market, and a nurse trained in one unit must know the others.
Gas springs and struts
The gas strut that holds up a car tailgate contains nitrogen at 100 to 200 psi, 690 to 1,380 kPa. Even a small cylinder stores that much pressure, so struts must not be drilled or burned. The pressure is rarely printed, and the force rating in newtons is the figure used when buying a replacement.
Seawater pressure
Every 10 metres of seawater adds about 100 kPa, 14.5 psi. At 1,000 metres a submersible carries 10.1 MPa, 1,470 psi, and at 3,000 metres 30.4 MPa, 4,410 psi. Oceanographers use MPa, while American subsea documents often quote kilo-psi.
Two routes to one answer
You can go from psi to kPa directly with 6.894757, or through bar: multiply by 0.0689476 and then by 100. If the results differ, a digit has been copied wrongly.
Apollo's one-third atmosphere
The Apollo command module held pure oxygen at 5 psi, 34.5 kPa, a third of sea-level pressure. A fire on the ground in 1967, in a capsule at 16.7 psi, 115 kPa, of pure oxygen, led to the change of procedures. The case shows how important pressure and gas composition are together.
Soda dispensers
A soft-drink dispenser regulates carbon dioxide at 40 psi, 276 kPa, for the syrup and 70 to 90 psi, 483 to 621 kPa, for the carbonator. A “convert psi to kPa” calculation lets a technician abroad match the settings with a kPa gauge.
Dental and workshop air
A dental handpiece is driven by air at 30 to 40 psi, 207 to 276 kPa, while a workshop spray gun needs 40 to 90 psi. Specifications from the manufacturers are in psi in America, and equipment sold in Australia carries kPa on its label.
Lawn-sprinkler valves
Garden valves are rated for 150 psi, 1,034 kPa, and household supply is 40 to 80 psi, 276 to 552 kPa. A line at 100 psi, 689 kPa, needs a pressure reducer. The Australian rule of thumb of 350 kPa for a supply to sprinklers equals about 51 psi.
Beer kegs
A keg of beer is kept at about 12 psi, 83 kPa, depending on temperature and carbonation. A cold cellar at 4 °C needs 10 to 12 psi, 69 to 83 kPa, and a warmer one more. Carbonation charts print psi, and homebrewers outside the US convert to kPa.
Swimming-pool filters
A pool filter has a normal clean pressure of 10 to 15 psi, 69 to 103 kPa, and should be backwashed when the gauge rises by 8 to 10 psi, 55 to 69 kPa. The manual is in psi in America and in kPa or bar elsewhere.
Engine oil
An engine oil pressure of 10 psi, 69 kPa, at idle and 40 to 60 psi, 276 to 414 kPa, at speed is normal for many cars. A low-pressure warning light comes on at about 5 to 7 psi, 34 to 48 kPa. Service manuals use psi in America and kPa in Australia.
Turbocharger boost
A turbo that produces 14.7 psi of boost doubles the absolute pressure in the intake, since boost of 14.7 psi, 101 kPa, is added to atmospheric 101.3 kPa. A gauge reading of 7 psi is 48 kPa of boost, 150 kPa absolute.
Fuel rail pressure
A modern port-injected petrol engine runs at 58 psi, 400 kPa, and a direct-injection system at 2,000 to 3,000 psi, 13.8 to 20.7 MPa. A gauge on the fuel rail in psi can be compared with workshop data in kPa after a “convert psi to kPa” calculation.
Hydro power head
A hydroelectric plant with a head of 100 metres has a pressure of 981 kPa at the turbine, 142 psi. For 300 metres the figure is 2.94 MPa, 427 psi. Engineers write these pressures in MPa, and American project documents in psi.
More values for convert psi to kPa
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 = 0.689476 kPa
- 0.5 psi = 3.44738 kPa
- 3 psi = 20.6843 kPa
- 4 psi = 27.579 kPa
- 7 psi = 48.2633 kPa
- 15 psi = 103.421 kPa
- 20 psi = 137.895 kPa
- 75 psi = 517.107 kPa
- 200 psi = 1,378.95 kPa
- 500 psi = 3,447.38 kPa
- 2,000 psi = 13,789.5 kPa
- 10,000 psi = 68,947.6 kPa
Traps with a “convert psi to kPa” calculation
The factor used backwards
From psi to kPa you multiply by 6.8948. If 30 psi came out as 4.35, you divided instead.
kPa mistaken for bar
One bar is 100 kPa. Reading 220 kPa as 220 bar would put the pressure a hundred times too high. Check the unit before inflating.
Gauge or absolute
Tyre pressure is gauge pressure. Do not add 101.3 kPa unless the specification asks for absolute pressure.
Short answers
How do I convert psi to kPa?
Multiply the psi figure by 6.8948.
How many kPa is 32 psi?
220.6 kPa.
How many kPa is 100 psi?
689.5 kPa.
How many psi is 100 kPa?
14.5 psi.
Does my number leave my device?
No, the calculation runs in your browser.
More pages and a wrap-up
For other pressure conversions see Convert psi to bar, Convert km to mi, Convert mi to km, Convert °C to °F, Convert °F to °C, Convert °F to °R, Convert m³ to yd³, Convert J to kWh, Convert dm to cm. The reverse direction is Convert kPa to psi.
In short, a “convert psi to kPa” calculation comes down to multiplying by 6.8948 and writing the unit beside the answer. Your number is computed locally, with no account and no upload.