Pressure Converter

Pressure is force per unit area, P = F / A. Its SI unit is the pascal (Pa), one newton per square meter. Weather reports use hPa or mbar, tyres psi or bar, blood pressure mmHg, and vacuum gauges Torr, microns or inches of mercury.

How to convert pressure units

Type a value into any field, and every other unit is calculated at once. For example, a tyre at 32 psi:

1. In bar: multiply by 0.0689476.

   32 × 0.0689476 = 2.206 bar

2. In kPa: multiply by 6.89476.

   32 × 6.89476 = 220.6 kPa

Vacuum in microns

A micron of vacuum is a micron of mercury, a thousandth of a millimeter of mercury. It is the same as a millitorr (mTorr), a thousandth of a Torr. HVAC technicians usually pull a system down to about 500 microns before charging it with refrigerant:

• 500 microns = 0.5 Torr = 66.66 Pa = 0.6666 mbar
• 500 microns = 0.00967 psi

Microns are an absolute pressure, while a vacuum gauge in inches of mercury shows how far below the atmosphere a system is. To convert such a reading, first take it away from the atmospheric pressure, 29.92 inHg at sea level. A reading of 29.9 inHg of vacuum leaves 0.02 inHg, which is about 508 microns.

Common conversions

Pressure units

• Pascal (Pa): Pascal is the SI unit of pressure. One pascal is equal to the pressure exerted by a force of one newton per square meter. It is widely used in scientific and engineering calculations.
  Conversion Factor: 1 Pa = 1 N/m²

• Hectopascal (hPa): Hectopascal is a unit of pressure equal to one hundred pascals. It is commonly used in meteorology to measure atmospheric pressure.
  Conversion Factor: 1 hPa = 100 Pa

• Kilopascal (kPa): Kilopascal is a unit of pressure equal to one thousand pascals. It is frequently used in building and construction, as well as scientific measurements.
  Conversion Factor: 1 kPa = 1,000 Pa

• Megapascal (MPa): Megapascal is a unit of pressure equal to one million pascals. It is commonly used in engineering and material science applications.
  Conversion Factor: 1 MPa = 1,000,000 Pa

• Bar (bar): Bar is a unit of pressure equal to one hundred thousand pascals. It is commonly used in industrial applications, such as measuring gas and liquid pressures.
  Conversion Factor: 1 bar = 100,000 Pa

• Pounds/inch² (psi): Pounds per square inch is an imperial unit of pressure commonly used in the United States and a few other countries. It represents the pressure exerted by a force of one pound on a one-square-inch area.
  Conversion Factor: 1 psi ≈ 6,894.76 Pa

• Pounds/foot² (psf): Pounds per square foot is an imperial unit of pressure. It signifies the pressure exerted by a force of one pound on a one-square-foot area.
  Conversion Factor: 1 psf ≈ 47.88 Pa

• Kilograms/meter² (kg/m²): Kilograms per square meter is a metric unit of pressure. It represents the pressure exerted by a force of one kilogram on a one-square-meter area.
  Conversion Factor: 1 kg/m² ≈ 9.80665 Pa

• Newtons/meter² (N/m²): Newtons per square meter is the SI unit for pressure and is equivalent to pascals. It measures the pressure exerted by a force of one newton on a one-square-meter area.
  Conversion Factor: 1 N/m² = 1 Pa

• Atmosphere (atm): Atmosphere is a unit of pressure that approximates the average atmospheric pressure at sea level. It is commonly used in meteorology and scuba diving.
  Conversion Factor: 1 atm ≈ 101,325 Pa

• Millimeter mercury (mmHg): Millimeter of mercury is a unit of pressure often used in medical and scientific applications, particularly in measuring blood pressure.
  Conversion Factor: 1 mmHg ≈ 133.32 Pa

• Inch mercury (inHg): Inch of mercury is a unit of pressure, primarily used in the United States. It represents the pressure exerted by a column of mercury one inch in height.
  Conversion Factor: 1 inHg ≈ 3,386.38 Pa

• Torr (Torr): Torr is a unit of pressure equivalent to one millimeter of mercury (mmHg). It is commonly used in vacuum measurements.
  Conversion Factor: 1 Torr = 1 mmHg

• Micron (mTorr): Micron, also known as millitorr, is a unit of pressure derived from Torr. It is equal to one thousandth of a Torr and is frequently used in high-vacuum applications.
  Conversion Factor: 1 mTorr ≈ 0.133322 Pa

• Millibar (mbar): Millibar is a unit of pressure equal to 1/1000 bar. It is commonly used in meteorology and aviation to measure atmospheric pressure.
  Conversion Factor: 1 mbar = 0.001 bar = 100 Pa

• Centimeter of water (cmH₂O): Centimeter of water is a unit of pressure commonly used in medical and hydrostatic applications. It represents the pressure exerted by a column of water one centimeter in height.
  Conversion Factor: 1 cmH₂O ≈ 98.0665 Pa

• Inch of water (inH₂O): Inch of water is a unit of pressure, frequently used in ventilation, HVAC systems, and weather measurements. It signifies the pressure exerted by a column of water one inch in height.
  Conversion Factor: 1 inH₂O ≈ 249.0889 Pa

• Foot of water (ftH₂O): Foot of water is a unit of pressure that represents the pressure exerted by a column of water one foot in height and is commonly used in hydrostatic calculations.
  Conversion Factor: 1 ftH₂O ≈ 2,989.067 Pa

Frequently asked questions

Is a Torr the same as a millimeter of mercury?

Almost. The Torr is defined as 1/760 of an atmosphere, and the millimeter of mercury as the pressure of a 1 mm column of mercury. They differ by about one part in seven million, so they are used interchangeably.

How many microns is a perfect vacuum?

Zero. A good deep vacuum is below 500 microns, and laboratory high vacuum is below 1 micron.