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Convert psi, bar, kPa, MPa, atmospheres, Torr, mmHg and inHg — with the absolute figure shown for gauge readings. A torque converter is included further down.
Torque is a different quantity from pressure, so it has its own converter below. It handles newton-metres (Nm), foot-pounds (ft-lb) and inch-pounds (in-lb) — the units used for tightening bolts and fasteners. "Nm to ft-lb" is one of the most searched conversions because tools and manuals mix the two.
| Pressure | Torque | |
|---|---|---|
| 1 bar | = 100 kPa = 14.504 psi |
100 Nm = 73.76 ft-lb 1 Nm = 0.7376 ft-lb 1 ft-lb = 1.3558 Nm 1 ft-lb = 12 in-lb 1 kgf-m = 9.807 Nm 120 Nm = 88.5 ft-lb |
| 1 atm | = 101.325 kPa = 14.696 psi | |
| 1 MPa | = 145.038 psi = 10 bar | |
| 1 psi | = 6.895 kPa | |
| 32 psi | = 220.6 kPa (common car tyre) | |
| 1 atm | = 760 Torr = 1013.25 mbar |
This is the distinction that most pressure conversions quietly ignore, and it is worth an entire atmosphere.
| Gauge pressure | Absolute pressure | |
|---|---|---|
| Measured from | Current atmospheric pressure | A perfect vacuum |
| Zero means | Same as the surrounding air | No pressure at all |
| Written as | psig, barg, kPa (g) | psia, bara, kPa (a) |
| Used by | Tyre gauges, most workshop equipment | Science, thermodynamics, vacuum work |
The calculator above converts the number you enter, then shows what it would be in absolute terms if it came from a gauge. For everyday tyre and equipment work the gauge figure is the one you want; for anything involving the behaviour of the gas itself, it is not.
| Unit | In pascals | Where you meet it |
|---|---|---|
| Pascal (Pa) | 1 | The SI unit — one newton per square metre. Very small in practice |
| Kilopascal (kPa) | 1,000 | Australian tyre placards, weather, building loads |
| Megapascal (MPa) | 1,000,000 | Concrete strength, hydraulics, material specifications |
| Millibar (mbar) | 100 | Meteorology — sea level is about 1013 mbar |
| Bar | 100,000 | European equipment, scuba, some tyre gauges |
| psi | 6,894.757 | Most workshop gauges, American equipment |
| Atmosphere (atm) | 101,325 | Chemistry, a reference point |
| Torr | 133.322 | Vacuum work. Defined as 1/760 atmosphere |
| mmHg | 133.322 | Blood pressure, older barometers |
| inHg | 3,386.4 | American aviation and weather |
Torr and mmHg are very nearly the same and often used interchangeably. Torr is defined as exactly 1/760 of an atmosphere; mmHg is defined from the density of mercury at 0 °C under standard gravity. They differ by about one part in seven million, which matters in metrology and nowhere else.
Australian vehicles carry a placard in kPa while most gauges and servo air hoses read psi, which is why this particular conversion gets done so often.
| psi | kPa | bar | Typical use |
|---|---|---|---|
| 26 | 179 | 1.79 | Lower end for a small car |
| 32 | 221 | 2.21 | Very common passenger car figure |
| 36 | 248 | 2.48 | Loaded car, larger vehicles |
| 40 | 276 | 2.76 | Light truck, towing |
| 50 | 345 | 3.45 | Some 4WD and van applications |
| 80–130 | 552–896 | 5.5–9.0 | Road bicycle tyres |
| 200 | 20,000 | 200 | Full scuba cylinder |
The two share a workshop and nothing else. Pressure is force spread over an area; torque is force applied at a distance from a pivot.
| Unit | In newton metres | Where you meet it |
|---|---|---|
| Newton metre (Nm) | 1 | The SI unit — Australian and European specifications |
| Foot-pound (ft-lb) | 1.3558 | American torque wrenches and manuals |
| Inch-pound (in-lb) | 0.11298 | Small fasteners, electronics, aviation |
| Kilogram-force metre (kgf-m) | 9.80665 | Older Japanese and European equipment |
There are exactly 12 inch-pounds in a foot-pound, which follows directly from twelve inches in a foot. It is the one torque conversion you can do in your head.
Torque specifications exist because both directions of error cause failures.
| Application | Typical range |
|---|---|
| Passenger car wheel nuts | 100–140 Nm (74–103 ft-lb) |
| 4WD and light truck wheel nuts | 120–180 Nm (89–133 ft-lb) |
| Alloy wheel nuts | Often lower — check the manual |
| Engine oil drain plug | 25–45 Nm (18–33 ft-lb) |
| Spark plugs | 15–30 Nm (11–22 ft-lb) |
| Bicycle stem bolts | 5–8 Nm (44–71 in-lb) |
How do you convert psi to bar?
Divide by 14.5038, since one bar is 14.5038 psi. So 100 psi is about 6.895 bar, and 32 psi is roughly 2.21 bar. Going the other way, multiply bar by 14.5038 to get psi.
How many psi is 1 bar?
14.5038 psi. Bar is a convenient unit because it is very close to one atmosphere — 1 bar is 100,000 pascals while a standard atmosphere is 101,325 — so bar and atmospheres are often used loosely as though interchangeable, though they are not identical.
How do I convert kPa to psi?
Divide by 6.895. Australian tyre placards are usually in kPa while most gauges read psi, so this is the conversion drivers do most: 220 kPa is about 32 psi, and 250 kPa is roughly 36 psi.
What is the difference between gauge and absolute pressure?
Gauge pressure is measured relative to the surrounding air, so zero means the same as atmospheric. Absolute pressure is measured from a perfect vacuum. A tyre gauge reading 32 psi is at about 46.7 psi absolute, because atmospheric pressure adds roughly 14.7 psi. Everyday gauges read gauge pressure; scientific and thermodynamic work uses absolute.
What is standard atmospheric pressure?
101,325 pascals by definition, which is 101.325 kPa, 1.01325 bar, 14.696 psi or exactly 760 Torr. Actual atmospheric pressure varies with weather and altitude, which is why weather reports quote it in hectopascals or millibars.
What is the correct tyre pressure for my car?
Use the placard on the driver's door jamb, inside the fuel flap or in the owner's manual — not the number on the tyre sidewall, which is the tyre's maximum rather than a recommendation. Pressures often differ front to rear, and many vehicles specify higher figures when heavily loaded or towing. Check when the tyres are cold.
Why do Australian tyre placards use kPa?
Because Australia is metric and the kilopascal is the SI-derived unit for pressure. Most gauges and service station air hoses still read psi, which is why the conversion is so commonly needed. As a rough guide, divide kPa by 7 to get psi — 220 kPa gives about 31, against a true 32.
What is the SI unit of pressure?
The pascal, defined as one newton per square metre. It is a very small unit — everyday pressures run to hundreds of kilopascals — so kPa and MPa are used in practice while bar, psi and atmospheres survive in particular industries.
What is the difference between Torr and mmHg?
Almost nothing. Torr is defined as exactly one seven-hundred-and-sixtieth of a standard atmosphere, while mmHg is defined from the density of mercury at 0 °C under standard gravity. They differ by about one part in seven million, so they are used interchangeably outside precision metrology.
Is torque the same as pressure?
No. Pressure is force distributed over an area, measured in pascals. Torque is force applied at a distance from a pivot, measured in newton metres. They are different physical quantities and there is no conversion between them, despite both appearing on workshop equipment.
How do I convert Nm to ft-lb?
Divide by 1.3558. So 100 Nm is about 73.8 ft-lb, and a typical 120 Nm wheel nut specification is roughly 88 ft-lb. There are exactly 12 inch-pounds in a foot-pound, which makes that conversion easy to do mentally.
What torque should wheel nuts be tightened to?
It depends on the vehicle — commonly 100 to 140 Nm for passenger cars and higher for 4WDs, but always check the manual for your model. Alloy wheels often specify lower figures than steel. Both errors cause failures: under-tightened nuts work loose, and over-tightening stretches or snaps studs and can warp a brake disc.
Pressure conversion is straightforward arithmetic with one complication that most tools skip: whether the number came from a gauge or is an absolute measurement. The gap is a full atmosphere, and it silently ruins gas-law calculations.
For tyres and workshop use the gauge figure is the right one — just use the placard rather than the sidewall, and check them cold.
For other measurement types, the unit converter covers ten categories, and the weight and force calculator handles the newtons that pressure is built from.