Units of Pressure & Conversions in SI, CGS and FPS

Pressure is a physical quantity that has wide uses in Science, especially, in fluid mechanics and hydrostatics. We need to deal with the pressure to know the nature of the flow of a fluid, to measure the amount of stress that a body can handle, to get forecast of weather, to study the behavior of gases, etc. Again, in medical purpose, the measurement of blood pressure is important. But the problem is that the pressure has several units to represent and different units are used for different purpose. So, we need to know all the units of pressure and their conversions. In this post, we are going to know these all things.

Contents in this article:

  1. What is Pressure?
  2. 5 Units of Pressure list
  3. Unit for measurement of pressure
  4. Discussion of all units of pressure
  5. Pressure units conversions

Units of Pressure list

Here is the list of units of Pressure.

  • Standard atmosphere (atm)
  • Pascals (Pa)
  • N/m2
  • dyn/cm2
  • PSI
  • Bar
  • Torr
  • Barad (Ba)
  • mmHg

SI units of Pressure

N/m2 is the SI unit of Pressure. It has another name as Pascal (Pa). French scientist Blaise Pascal has given a law of pressure in fluids, called Pascal’s Law. For this, the SI unit of pressure is named after him.

1 Pascal = 1 N/m2 = 10 dyn/cm2.

Units for pressure measurement

Although, there are so many units of pressure, but one cannot use any unit to measure any pressure. Different units are used in measurement of different types of pressures. See the following table.

Serial No.PressureUnit
1Atmospheric pressure
or Air pressure
atm
2Fluid pressurePascal (Pa)
3Mechanical pressureN/m2
4Blood pressuremmHg
5Vacuum pressureTorr
Units of measurement of pressure

However, there are multiple units to present same kind of pressure. For example: Both the Bar and atm can be used to represent the pressure of gas.

Brief discussions of pressure measuring units

atm

The mostly used unit of pressure is atm. It represents the standard atmospheric pressure. 1 atm means the pressure of 76 cm mercury column. It is the most convenience unit to represent the pressure of air and gases. Again, 1 atm equals to 101325 Pascals.

Pascal (Pa)

Pascal is another common unit of pressure. It is the SI unit of pressure. This unit is used to represent the pressure of liquids. It is named after the French scientist Blaise Pascal.

PSI

The full form of PSI is Pound per square inch. This is the unit of pressure in FPS unit. PSI is a popular unit of pressure in United State of America. American engineers also use Kilo-pound per square inch (ksi) unit to write the value of pressure.

1 psi equals to 6895 Pascals.

Bar

Bar is the metric unit of pressure. Atmospheric pressure and the pressure of gases are usually written in Bar unit.

1 Bar equals to 105 Pascals.

Torr

The pressure of 1 mm Hg is equal to one Torr. Small amount pressures like vacuum pressure is measured in the unit of Torr. It is named after the Scientist Torricelli.

1 atm equals to 760 Torr.

N/m2

This is the SI unit of pressure. It arises from the definition of pressure which is defined as the amount of force per unit area. Therefore, the SI unit of the pressure is Newton per square meter. Its CGS counterpart is dyn/cm2.

1 N/m2 equals to one Pascal (Pa).

Barad (Ba)

Barad is another metric unit of pressure. It is a non-SI unit. Barad unit has other names as Barye, Bary, Baryd, etc. 1 Barad means 1 dyne force per square centimeter i.e. 1 Ba = 1 dyn/cm2 which is equal to 0.1 Pascal.

Conversion of units of pressure

Sometime, we need to convert pressure units. Here is the table that gives the conversion of units of pressure. In the following table, we have related all units of pressure with Pascal (Pa) unit.

Pressure in other unitsPressure in Pascal (Pa)
1 atm101325 Pa
1 Bar105 Pa
1 psi6894.76 Pa
1 N/m21 Pa
1 Torr133.32 Pa
1 Barad0.1 Pa
Conversion of units for pressure

Using this table, one can convert the value of pressure from one unit to Pascal unit. Again, all other units like atm, Bar, psi, Torr, etc. units can be related to each other by using this table.

Write in comments:

  1. Can you convert N/m2 into dyn/cm2? Then 1 N/m2 equals to how much dyn/cm2?
  2. What is the unit of blood pressure?

This is all from this article on unit of pressure and its conversion to other reasonable unit. If you have any doubt on this topic you can ask me in the comment section.

Thank you!

Related posts:

  1. Different equations of Force
  2. Errors in measurement
  3. Pascal’s Law of pressure

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