Pressure Converter
Convert psi, bar, kPa, Pa, atm, mmHg, torr, inHg, kgf/cm² and inches of water with exact or conventional factors.
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Tool guide
What this tool does
Pressure Converter handles tyre, weather, medical, hydraulic and laboratory pressure units. It uses exact SI factors where they exist and the standard conventional values for mercury and water columns.
Pressure is one of the most fragmented measurements in daily life. Tyre gauges read psi or bar, weather maps use hectopascals or millibars, blood pressure is recorded in millimetres of mercury, Indian compressors and boilers are often rated in kg/cm², and engineering specifications use MPa or ksi. Using the wrong factor can mean an underinflated tyre or a fitting rated below the system pressure.
The pascal is the base unit here. Bar (100,000 Pa) and the standard atmosphere (101,325 Pa) are exact, and the torr is defined as 1/760 of an atmosphere. Psi is derived from the exact pound and inch with standard gravity, giving about 6,894.757 Pa. Mercury and water columns use the conventional values from NIST tables, such as 133.322 Pa per mmHg. The typical pressures table helps you sanity-check a result, and all conversions run locally.
How to use Pressure Converter
- Enter the pressure in the Value field.
- Choose the From unit, for example Pound per square inch.
- Choose the To unit, for example Bar, and read the Result.
- Swap the units or change Decimal places as needed.
- Compare your result with the Typical pressures table.
- Convert a list of readings at once with Batch convert and download them as CSV.
Tips for better results
- One bar is roughly 14.5 psi, and 1 kg/cm² is very close to 1 bar (0.98 bar).
- One hectopascal equals one millibar, so weather values convert without change.
- mmHg and torr differ by less than one part in seven million, so they are interchangeable for most purposes.
Common use cases
- Setting tyre pressure from a placard in psi using a gauge that reads bar or kPa.
- Converting barometric pressure between hPa, inHg and mmHg for weather stations.
- Matching pump, compressor and pressure-washer ratings across catalogues.
- Converting material strengths between MPa and ksi in engineering work.
Common mistakes to avoid
- Mixing gauge pressure with absolute pressure, which differ by about one atmosphere.
- Treating kgf/cm² as exactly 1 bar when precision matters; it is 0.980665 bar.
- Confusing kPa with MPa in hydraulic specifications, a factor of 1,000.
Frequently asked questions
How many psi is 1 bar?
One bar is about 14.5038 psi. Conversely, 1 psi is about 0.0689 bar, so 32 psi is roughly 2.21 bar.
What is standard atmospheric pressure?
The standard atmosphere is defined as exactly 101,325 Pa, which is 1.01325 bar, 760 mmHg or about 14.696 psi.
Is kg/cm² the same as bar?
Almost. One kilogram-force per square centimetre is 98,066.5 Pa, or 0.980665 bar. The 2% difference matters for precise ratings.
Why is blood pressure measured in mmHg?
Early instruments measured pressure by the height of a mercury column, and medicine kept the unit. One mmHg is about 133.3 Pa, so 120 mmHg is roughly 16 kPa.
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