One pressure converter for tyres, weather, medicine and engineering
Pressure is quoted in more units than almost any other quantity, and this pressure converter handles all the common ones: pascals, kilopascals and megapascals, bar and millibar, the standard atmosphere, kgf/cm², psi, mmHg, inHg, torr and centimetres or inches of water. Type a reading and see it in every unit together.
Typical uses: matching a car manual in psi to a petrol-station gauge in bar, reading an Indian compressor dial in kg/cm², turning a US weather report in inches of mercury into hectopascals, converting a blood-pressure reading for a medical paper, or checking a hydraulic or cylinder rating in MPa against a spec sheet in psi.
How to use the Pressure Converter
- Enter the reading in the Value box — for example 32 for a tyre at 32 psi.
- Choose its unit in From; search “psi”, “bar”, “kg/cm” or “mmHg”.
- Choose the unit you need in To, or press the round swap button to reverse.
- Read the converted pressure and the formula. Adjust Precision and press Copy as needed.
- Use the list of every pressure unit to compare readings, or tap a common conversion such as “1 bar → psi”.
Pressure Converter features
Fifteen units in four groups
SI and metric, atmospheres, imperial (psi, psf) and liquid-column units (mmHg, inHg, torr, cmH₂O, inH₂O).
Tyre-friendly
psi, bar, kPa and kgf/cm² — the four units you meet on tyre placards and air pumps worldwide.
Weather units
Hectopascals and millibars (identical) and inches of mercury for barometers and aviation.
Precise conventional values
mmHg, inHg and water-column units use their conventional definitions, so results match standards tables.
Torr and mmHg kept distinct
They differ by less than one part in six million, but the converter treats them as the separate units they are.
Pressure conversion factors
The SI unit of pressure is the pascal, one newton of force per square metre — a very small pressure, which is why kPa and MPa are used in practice. The standard atmosphere was fixed at exactly 101,325 Pa in 1954. Imperial pressure (psi) comes from the pound-force acting on one square inch, using standard gravity of 9.80665 m/s².
| Unit | Value in pascals | Typical use |
|---|---|---|
| Kilopascal (kPa) | 1,000 | Tyres (Canada, Australia), engineering |
| Hectopascal (hPa) = millibar (mbar) | 100 | Weather maps |
| Bar | 100,000 | Tyres, diving, industry in Europe and India |
| Standard atmosphere (atm) | 101,325 (exact) | Chemistry, reference conditions |
| Kilogram-force per cm² (kgf/cm²) | 98,066.5 (exact) | Compressors and older gauges, India |
| Pound per square inch (psi) | ≈ 6,894.757 | Tyres and hydraulics in the US and UK |
| Millimetre of mercury (mmHg) | 133.322387415 (conventional) | Blood pressure |
| Torr | 101,325/760 ≈ 133.3224 | Vacuum systems |
| Inch of mercury (inHg) | 3,386.389 (conventional) | US weather and aviation altimeters |
| Centimetre of water (cmH₂O) | 98.0665 | CPAP machines, ventilators |
| Inch of water (inH₂O) | 249.08891 | Gas supply, HVAC ducts |
Worked examples
Tyre pressure, psi to bar — divide by 14.5038. A placard saying 32 psi means 32 ÷ 14.5038 = 2.21 bar, or 220.6 kPa. Going the other way, 2.2 bar is 31.9 psi.
kgf/cm² to psi — multiply by 14.2233. A compressor dial reading 2.5 kg/cm² is 35.6 psi, a little less than 2.5 bar would be (36.3 psi), because 1 kgf/cm² is 0.980665 bar.
Weather, hPa to inHg — divide by 33.86389. The standard sea-level pressure of 1,013.25 hPa is 29.92 inHg.
Blood pressure, mmHg to kPa — multiply by 0.133322. A reading of 120/80 mmHg is 16.0/10.7 kPa. This is a unit conversion only and not medical advice.
Diving, bar to psi. A scuba cylinder filled to 200 bar holds about 2,900 psi.
Gauge pressure vs absolute pressure
Most everyday gauges read gauge pressure — the pressure above the surrounding air. A tyre at 32 psi on the gauge actually holds about 32 + 14.7 = 46.7 psi absolute at sea level. Engineers mark the difference as psig and psia, or “bar(g)” and “bar(a)”. Convert the number first with this tool, then add or subtract atmospheric pressure (1 atm = 14.696 psi = 1.01325 bar) if you need to switch between gauge and absolute.
Pressure, temperature and energy often appear together in gas and heating problems; see the temperature converter and the energy converter for the other half of the calculation.
Common pressure conversions
| From | To |
|---|---|
| 1 bar | 14.50377377 psi |
| 1 psi | 6.894757293 kPa |
| 1 psi | 0.06894757293 bar |
| 1 atm | 14.69594878 psi |
| 1 atm | 1.01325 bar |
| 1 atm | 759.9998917 mmHg |
| 1 kgf/cm² | 14.22334331 psi |
| 1 kgf/cm² | 0.980665 bar |
| 1 MPa | 145.0377377 psi |
| 1 inHg | 33.86389 hPa |
| 1 mmHg | 133.3223874 Pa |
| 10 cmH₂O | 9.80665 hPa |
Pressure Converter FAQ
How do I convert psi to bar?
Divide by about 14.5038 (1 bar = 14.503774 psi). For example, 35 psi ÷ 14.5038 = 2.41 bar. The pressure converter shows the exact factor with every result.
How many psi is 1 bar?
One bar is 14.5038 psi. One standard atmosphere is slightly more: 14.6959 psi.
Is kg/cm² the same as bar?
Nearly, but not exactly. 1 kgf/cm² is 0.980665 bar (98.0665 kPa), so a gauge in kg/cm² reads about 2% higher than one in bar for the same pressure.
Are mmHg and torr the same?
Almost. One torr is exactly 1/760 of a standard atmosphere, while the conventional millimetre of mercury is 133.322387415 Pa. They differ by about 0.000014%, which only matters in precise metrology.
Is a hectopascal the same as a millibar?
Yes. 1 hPa = 1 mbar = 100 Pa. Weather services switched from millibars to hectopascals without changing the numbers.
What is standard atmospheric pressure?
Exactly 101,325 Pa, which equals 1.01325 bar, 1,013.25 hPa, 760 torr, about 14.696 psi and about 29.92 inHg.