Pressure Unit Converter

Convert between units of pressure.

Supported Units

• Pascal (Pa): The pascal is the SI unit of pressure, defined as one newton of force per square meter. Named after French mathematician and physicist Blaise Pascal, it is the foundation for related units like the hectopascal used in weather reports. Since one pascal is a very small amount of pressure, practical applications typically use kilopascals (kPa) or megapascals (MPa). In materials engineering, stress and tensile strength are expressed in megapascals or gigapascals.
• Hectopascal (hPa): The hectopascal equals 100 pascals and is the standard unit for atmospheric pressure in meteorology worldwide. Standard atmospheric pressure is 1013.25 hPa, and weather reports use hectopascals when describing high and low pressure systems and typhoon central pressures (such as 950 hPa). One hectopascal is exactly equal to one millibar. The international meteorological community switched from millibars to hectopascals in 1992.
• Kilopascal (kPa): The kilopascal equals 1,000 pascals and is commonly used for tire pressure specifications. A typical passenger car tire is inflated to about 220 to 250 kPa. Some blood pressure monitors also display readings in kilopascals. In industry, gas pipeline pressures and hydraulic system pressures may be expressed in kPa. Standard atmospheric pressure is approximately 101.325 kPa.
• Megapascal (MPa): The megapascal equals one million pascals and is widely used in materials and structural engineering. Concrete compressive strength typically ranges from 21 to 35 MPa, and steel tensile strength ranges from about 400 to 800 MPa. Hydraulic equipment operates at pressures of tens of megapascals. The unit is essential for specifying material properties, bolt preloads, and pressure vessel ratings in industrial applications.
• Bar (bar): The bar is a unit of pressure equal to 100,000 pascals, which is very close to standard atmospheric pressure (101,325 Pa). This convenient relationship makes it widely used in industry. Scuba tank pressure is typically around 200 bar, espresso machines extract at about 9 bar, and fire extinguishers are pressurized to several bar. While not an SI unit, the bar is accepted for use with the SI in many countries.
• Atmosphere (atm): The standard atmosphere is a unit of pressure defined as exactly 101,325 pascals. It approximates the average atmospheric pressure at sea level on Earth. In diving, pressure increases by roughly 1 atm for every 10 meters of water depth, so at 30 meters the total pressure is about 4 atm. In chemistry, standard conditions for gases are defined at 0 degrees Celsius and 1 atm, making it a fundamental reference in thermodynamics and gas law calculations.
• Millimeter of mercury (mmHg): The millimeter of mercury is a unit of pressure based on the height of a mercury column, equal to approximately 133.3 pascals. It is the universal standard for reporting blood pressure in medicine: normal blood pressure is below 120 mmHg systolic and 80 mmHg diastolic. The unit originates from Torricelli's 1643 experiment, which showed that atmospheric pressure supports a mercury column of about 760 mm. One mmHg is nearly identical to one torr.
• Pound per square inch (psi): The pound per square inch is a unit of pressure expressing force in pounds-force applied to an area of one square inch. It is widely used in the United States and United Kingdom. Car tire pressure in the US is typically 30 to 35 psi, and industrial compressed air systems commonly operate at 90 to 150 psi. Fire sprinkler systems, natural gas pipelines, and hydraulic tools all use psi ratings. One psi equals approximately 6,895 pascals.
• Torr (Torr): The torr is a unit of pressure named after Italian physicist Evangelista Torricelli. It is defined as exactly 1/760 of a standard atmosphere, approximately 133.3 pascals. The torr is widely used in vacuum technology, particularly in semiconductor manufacturing, where process chambers operate at pressures from 10 to the minus 3 to 10 to the minus 8 torr. While nearly identical to the millimeter of mercury, the torr is defined independently.

How to Use

1. Select the unit you want to convert from in the "From" dropdown.

2. Select the unit you want to convert to in the "To" dropdown.

3. Enter a value and the result will be displayed in real time.

4. Use the swap button to reverse the conversion direction.