Pressure Converter
Convert between PSI, bar, kilopascal, atmosphere, mmHg, inHg, Pascal, megapascal, and Torr instantly.
How to use the pressure converter
Enter your pressure value in the "From Value" field and select the appropriate pressure unit from the dropdown menu. Choose your target unit in the "To Value" section, and the converted result will appear instantly. Use the swap button to quickly reverse the conversion direction. All calculations happen in your browser for complete privacy and instant results.
This converter handles all major pressure units used in engineering, automotive, meteorology, and scientific applications. Whether you're checking tire pressure, calibrating equipment, or working with weather data, this tool provides precise conversions based on international standards. The tool uses exact conversion factors to ensure accuracy for professional and educational use.
Pressure measurements are fundamental in many fields, from hydraulic systems to atmospheric science. Understanding how to convert between different units helps ensure safety, accuracy, and proper communication across different industries and regions that may use different pressure standards.
Understanding pressure measurements
SI units and Pascal
The Pascal (Pa) is the SI unit for pressure, defined as one newton per square meter (N/m²). Named after Blaise Pascal, who made significant contributions to fluid mechanics and pressure theory, the Pascal is the standard unit for scientific and engineering calculations worldwide. For practical applications, kilopascals (kPa) and megapascals (MPa) are commonly used to avoid large numbers. The International Bureau of Weights and Measures (BIPM)defines Pascal as the official SI unit for pressure.
Atmospheric pressure
Standard atmospheric pressure is 101.325 kPa (14.696 PSI, 1 atm, 760 mmHg) at sea level. This pressure is caused by the weight of Earth's atmosphere above us. Atmospheric pressure decreases with altitude, which is why pressure cooking requires different times at high elevations and why aircraft cabins are pressurized. Weather systems are driven by differences in atmospheric pressure, with high pressure typically indicating stable weather and low pressure often associated with storms.
PSI and imperial units
PSI (pounds per square inch) is commonly used in the United States for tire pressure, pneumatic tools, and many industrial applications. One PSI equals the pressure exerted by one pound-force applied to an area of one square inch. While not an SI unit, PSI remains widely used in automotive and industrial settings in countries that use imperial measurements. Tire pressure is typically measured in PSI in the US, while most other countries use bar or kilopascals.
Bar and metric units
The bar is a metric unit of pressure equal to 100,000 Pascals, approximately equal to atmospheric pressure. It's commonly used in meteorology, diving, and industrial applications in many countries. One bar is slightly less than standard atmospheric pressure (1 atm = 1.01325 bar). The millibar (mbar) is often used for weather reporting, where typical atmospheric pressure ranges from about 950 to 1050 millibars.
Mercury column units
mmHg (millimeters of mercury) and inHg (inches of mercury) originated from barometers that used mercury columns to measure atmospheric pressure. These units are still used in medicine for blood pressure measurements and in some industrial applications. Torr is another unit based on mercury column height, where 1 Torr equals 1 mmHg. These units are particularly useful when dealing with vacuum systems or low-pressure applications where the pressure is a small fraction of atmospheric pressure.
Gauge vs absolute pressure
Understanding the difference between gauge and absolute pressure is crucial for accurate measurements. Gauge pressure measures pressure relative to atmospheric pressure, while absolute pressure measures pressure relative to a perfect vacuum. Most pressure gauges show gauge pressure, which can be negative (indicating vacuum). Absolute pressure is always positive and equals gauge pressure plus atmospheric pressure. This distinction is important in engineering calculations, fluid dynamics, and when working with vacuum systems.
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Frequently Asked Questions
What is standard atmospheric pressure?
Standard atmospheric pressure is 101.325 kPa (14.696 PSI, 1 atm, 760 mmHg). This is the average pressure at sea level on Earth and serves as a reference point for many pressure measurements.
How do I convert PSI to bar?
To convert PSI to bar, multiply the pressure in PSI by 0.0689476. For example, 100 PSI equals approximately 6.89476 bar. This conversion is commonly used in automotive and industrial applications.
What is the difference between gauge and absolute pressure?
Gauge pressure measures pressure relative to atmospheric pressure, while absolute pressure measures pressure relative to a perfect vacuum. Gauge pressure can be negative, but absolute pressure is always positive. Most pressure gauges show gauge pressure.
How do I convert mmHg to PSI?
To convert mmHg to PSI, divide the pressure in mmHg by 51.715. For example, 760 mmHg (standard atmospheric pressure) equals approximately 14.696 PSI.
What is Pascal in pressure measurement?
Pascal is the SI unit for pressure, defined as one newton per square meter. It's named after Blaise Pascal and is the standard unit for scientific pressure measurements worldwide.