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To convert a pressure from pounds per square inch (psi) to pascals (Pa), multiply by 6,894.76.
The number is the psi's own definition worked out in SI: one pound-force (4.448222 N) spread over one square inch (0.00064516 m²) is 4.448222 ÷ 0.00064516 = 6,894.76 N/m², and a newton per square meter is precisely a pascal. Because the factor is close to 7,000, a quick estimate is psi × 7,000, high by about 1.5%.
A fastener datasheet lists a proof stress of 120 psi for a gasket material, and a finite-element model needs the value in SI base units:
| psi | Pa |
|---|---|
| 1 | 6,894.76 |
| 5 | 34,473.8 |
| 10 | 68,947.6 |
| 14.696 | 101,325 |
| 50 | 344,738 |
| 100 | 689,476 |
Nobody reads a gauge in pascals — the unit is inconveniently small for hardware, which is exactly why kPa, bar and psi exist. But every formula that connects pressure to the rest of mechanics wants pascals, because Pa = N/m² cancels cleanly against kilograms, meters and seconds. Force on a hydraulic piston, stress in a pipe wall, the ρgh of a liquid column, the pressure term in Bernoulli's equation — feed them psi and the units simply do not close. The standard workflow is therefore: convert once at the boundary (psi × 6,894.76), compute everything in SI, and convert back only for the final report. Doing the conversion in the middle of a calculation, or worse, twice, is one of the classic ways unit errors creep into engineering spreadsheets. The one thing the conversion does not do is change the reference frame: a gauge reading in psig becomes gauge pascals, and thermodynamic formulas that need absolute pressure still need 101,325 Pa added afterwards.
To convert a pressure from pounds per square inch (psi) to kilopascals (kPa), multiply by 6.89476.
The factor is the pascal definition of the psi divided by a thousand: one pound-force spread over one square inch works out to 6,894.76 N/m², so 6.89476 kPa. For mental arithmetic, multiplying by 7 lands within 1.5% — close enough to sanity-check any gauge reading before trusting the exact figure.
Two anchors cover most of what a gauge will ever show:
A US tire gauge reads 32 psi and the vehicle's door placard — printed for the Canadian market — specifies cold inflation in kPa:
The placard almost certainly says 220 kPa. Same tire, same air, two labels.
| psi | kPa |
|---|---|
| 1 | 6.89 |
| 5 | 34.47 |
| 10 | 68.95 |
| 14.696 | 101.33 |
| 30 | 206.84 |
| 32 | 220.63 |
| 50 | 344.74 |
| 100 | 689.48 |
| 150 | 1,034.2 |
Nearly every psi figure encountered outside a laboratory is psig: pressure measured relative to the surrounding atmosphere, which is what a Bourdon-tube gauge physically reports. Kilopascal figures, by contrast, arrive from both conventions — automotive and pneumatic documents use gauge kPa, while meteorology and thermodynamics work in absolute terms. The multiplication by 6.89476 is identical either way; what changes is whether 101.325 kPa needs to be added afterwards. A 32 psig tire is at 220.6 kPa gauge but roughly 322 kPa absolute, and gas-law calculations fed the first number when they need the second are wrong by nearly half. When a converted value feeds anything beyond another gauge — a solubility table, a boiling-point chart, a compressor sizing formula — carry the g or the a along with the digits.
To convert a pressure or stress from pounds per square inch (psi) to megapascals (MPa), multiply by 0.00689476.
Because the factor is awkward at this scale, engineering practice leans on the thousand-fold version: 1 ksi (1,000 psi) = 6.89476 MPa. Stress values in US materials tables are usually quoted in ksi precisely so that the MPa conversion is a single clean multiplication.
A US structural drawing calls for A36 steel, minimum yield strength 36,000 psi, and the analysis software is configured in SI:
That 248 MPa figure is exactly how the same steel grade appears in metric references.
| psi | MPa |
|---|---|
| 100 | 0.689 |
| 1,000 | 6.895 |
| 3,000 | 20.68 |
| 4,000 | 27.58 |
| 10,000 | 68.95 |
| 36,000 | 248.2 |
| 60,000 | 413.7 |
The psi-to-MPa conversion lives mostly in materials engineering, where the quantity is stress — force per unit of cross-section — rather than fluid pressure, and the numbers run thousands of times higher than anything a pipe gauge shows. Concrete is the everyday example: American practice specifies compressive strength as 3,000/4,000/5,000 psi concrete, while the rest of the world writes 20/25/30 MPa for the same grades (the round metric numbers and the round imperial numbers do not quite coincide — 4,000 psi is 27.6 MPa, not 25 — so "equivalent" grades in tables are conventions, not conversions). Steel properties, bolt proof loads, weld strengths and pressure-vessel allowables repeat the pattern, with ksi as the imperial working unit.
One consequence of the stress context: gauge-versus-absolute, the trap that haunts every fluid-pressure conversion, is irrelevant here — stress has no atmosphere to be relative to. The trap that replaces it is precision theater. A yield strength known to two significant figures does not become better known by being converted to 248.2114 MPa; matching the stated precision of the source figure is part of converting it correctly.
To convert from pound per square inch (psi) to hectopascal (hPa), use the following formula:
hectopascal (hPa)
= 11000 × 10.00014503768078 × 10× pound per square inch (psi)
= 1100 × 10.00014503768078× pound per square inch (psi)
= 68.947600004501395751× pound per square inch (psi)
With 10.00014503768078 is the ratio between the base units kilopascal (kPa) and kilopound per square inch (ksi).
To convert a pressure from pounds per square inch (psi) to millibars (mbar), multiply by 68.948.
One psi equals 6,894.76 Pa, and a millibar is exactly 100 Pa, so the factor is 68.9476. The most useful anchor pairs the two systems' round numbers: 14.5 psi ≈ 1,000 mbar = 1 bar.
A US-built compressor delivers a maximum of 8.7 psi boost, and the European test bench instrumentation reads in millibars:
The bench should therefore record just under 600 mbar of gauge pressure at full boost.
| psi | mbar |
|---|---|
| 0.5 | 34.5 |
| 1 | 68.9 |
| 8.7 | 600 |
| 14.5 | 1,000 |
| 14.696 | 1,013.25 |
| 30 | 2,068 |
Psi and mbar overlap in the low-pressure regime where both automotive and process industries operate internationally. Turbocharger boost is the emblematic case — American tuners speak of "10 psi of boost" while European engine-management systems log manifold pressure in mbar (absolute, at that: 10 psi boost at sea level is roughly 1,700 mbar absolute, a distinction that has confused more than one remap). Gas-burner supply pressures, leak-test specifications, and pneumatic-instrument ranges cross the same divide: a US spec of 0.5 psi becomes 34.5 mbar on a European manometer. The gauge-versus-absolute trap is the one that actually bites, because mbar instruments in meteorology read absolute while psi gauges on equipment almost always read relative to ambient — the ×68.948 arithmetic is identical either way, but forgetting to add the ~1,013 mbar of atmosphere shifts an answer by more than any plausible boost pressure. Anchoring on "14.5 psi is one bar of gauge pressure, two bar absolute" keeps the frames straight.
To convert a pressure from pounds per square inch (psi) to bar, multiply by 0.0689476 — or, equivalently, divide by 14.5038.
The bar is defined as exactly 100,000 Pa and the psi is 6,894.76 Pa, so one psi is 0.0689476 bar. The relationship worth memorizing runs the other way: 1 bar ≈ 14.5 psi, and one standard atmosphere is 14.696 psi = 1.01325 bar — which is why "about 1 bar" and "about 15 psi" both serve as shorthand for atmospheric pressure.
A US-spec scuba cylinder is filled to 3,000 psi and a European dive computer expects the reading in bar:
That is the familiar "200 bar" class of cylinder — the two markets rate the same tank in different units.
| psi | bar |
|---|---|
| 1 | 0.0689 |
| 10 | 0.689 |
| 14.696 | 1.0133 |
| 30 | 2.068 |
| 32 | 2.206 |
| 50 | 3.447 |
| 100 | 6.895 |
| 150 | 10.34 |
| 3,000 | 206.84 |
Industrial pneumatics is where this conversion earns its keep, and it is also where a quiet suffix convention matters. European compressed-air systems are specified in barg — bar gauge — so a "7 bar network" and a "100 psi shop line" are the same installation (7 barg = 101.5 psig). Process engineering documents sometimes switch to bara (bar absolute) for thermodynamic work, and the difference between the two is almost exactly one atmosphere. The arithmetic on this page converts the unit, not the reference frame: 100 psig is 6.89 barg, and only becomes about 7.90 bara after adding the atmosphere back. Scuba deserves its own caution in the same spirit — cylinder working pressures are gauge figures, but the gas planning math (how many liters of breathable air a 12 L / 200 bar tank holds) silently treats them as absolute multiples, which works only because 1 atm is small against 200 bar. At low pressures that shortcut stops being harmless.
To convert from pound per square inch (psi) to torr (torr), use the following formula:
torr (torr)
= 11000 × 10.00014503768078 × 760000101325× pound per square inch (psi)
= 51.714952877790338782× pound per square inch (psi)
With 10.00014503768078 is the ratio between the base units kilopascal (kPa) and kilopound per square inch (ksi).
To convert from pound per square inch (psi) to meter of water @ 4°C (mH2O), use the following formula:
meter of water @ 4°C (mH2O)
= 11000 × 10.00014503768078 × 19.80665× pound per square inch (psi)
= 0.70306985570507151526× pound per square inch (psi)
With 10.00014503768078 is the ratio between the base units kilopascal (kPa) and kilopound per square inch (ksi).
To convert from pound per square inch (psi) to millimeter of mercury (mmHg), use the following formula:
millimeter of mercury (mmHg)
= 11000 × 10.00014503768078 × 10.133322× pound per square inch (psi)
= 51.715095786517900835× pound per square inch (psi)
With 10.00014503768078 is the ratio between the base units kilopascal (kPa) and kilopound per square inch (ksi).
To convert from pound per square inch (psi) to kilopound per square inch (ksi), use the following formula:
kilopound per square inch (ksi)
= 11000× pound per square inch (psi)
= 0.001× pound per square inch (psi)
To convert from pound per square inch (psi) to Inch of mercury (inHg), use the following formula:
Inch of mercury (inHg)
= 11000 × 10.000491154× pound per square inch (psi)
= 2.0360212886385940051× pound per square inch (psi)
A pound per square inch (PSI) is a unit of pressure commonly used in the imperial system (which is standard in the United States).
It measures the amount of force applied over a single square inch of area.
PSI is a critical measurement for safety and performance in many common items, including:
Vehicle Tires: Proper tire pressure (PSI) ensures optimal handling, fuel efficiency, and tire life. You can find the recommended level on a sticker inside the driver's door.
Home Water Pressure: Affects everything from shower performance to how well appliances like dishwashers and washing machines function.
Sports Equipment: Items like footballs, basketballs, and soccer balls require a specific PSI to perform correctly and safely.
Tools: Air compressors, pressure washers, and paint sprayers all have specific PSI ratings for safe and effective operation.
While PSI is standard in the imperial system, scientific and international contexts use metric (SI) units like the Pascal (Pa) and the bar.
PSI to Pascal (Pa): The official SI unit for pressure.
1 PSI ≈ 6,894.76 Pascals (or 6.895 kilopascals, kPa).
PSI to Bar: A common unit in automotive and weather contexts. 1 bar is roughly equal to atmospheric pressure at sea level.
1 PSI ≈ 0.0689 bar.
The term "PSI" can be specified further to give more context:
PSIG (Pound-force per square inch gauge): Measures pressure relative to the surrounding atmospheric pressure. This is the most common measurement, used by a standard tire gauge.
PSIA (Pound-force per square inch absolute): Measures pressure relative to a perfect vacuum (absolute zero pressure).
The formula is: PSIA = PSIG + local atmospheric pressure.
PSID (Pound-force per square inch differential): Measures the difference in pressure between two separate points in a system, such as across a filter or valve.