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Contents

## Related Tools

- Force and area to pressure converter
- Pressure and area to force converter
- Pressure to liquid level calculator
- Liquid level to pressure calculator

## User Guide

This converter and dynamic conversion scale will calculate the equivalent pressure value from one pressure measurement unit to another and generate a conversion table based on the selected units.

- Enter the value you want to convert in the upper input box.
- Select the corresponding units from the upper pull down options.
- Select the units to convert to, from the lower pull down options.
- The conversion will show in the lower text box.

You can use this converter to copy and paste values as well, after pasting a value, just click/touch one of the text boxes or select a unit to convert the value.

## Conversion Guide

Convert pressure units with the pressure unit converting tool, look up a conversion from the tables, identify a pressure unit and its group association with other pressure units, or find the relevant pressure conversion factor in pascals.

### Conversion Tables

Choose a look up table for a specific pressure conversion application.

- Tyre pressure conversion for cars, trucks, cycles, motorbikes or aircraft
- Barometric conversion for mbar, hPa, psi, inHg, mmHg & Torr
- Vacuum conversion for % vac, mbar, hPa, psi, inHg, mmHg & Torr
- Altitude to pressure conversion from feet or metres to mbar, psi, mmHg & inHg
- I/P & P/I conversion for current and pneumatic signal control instrumentation
- E/P & P/E conversion for voltage and pneumatic signal control instrumentation

### Conversion Factors

The following list shows each pressure unit and its equivalent value converted into pascals (Pa). The pascal is the SI unit for measuring pressure.

#### Unique Conversion Factors

These units have an internationally agreed definition for the conversion factor, some have an exact value with very few digits, while others have a lot of digits and may vary very slightly between reference sources, depending on the level of precision used when calculating the values.

Symbol | Name | Pascals Value |
---|---|---|

bar | Bar | 100,000 |

psi, pfsi, lb/in², lbf/in² | Pounds Force Per Square Inch | 6894.75729316836 … |

mbar, mb, mbr | Millibar | 100 |

N/m² | Newton Per Square Metre | 1 |

Pa | Pascal | 1 |

hPa | Hectopascal | 100 |

kPa | Kilopascal | 1,000 |

MPa | Megapascal | 1,000,000 |

kg/cm², kgf/cm² | Kilogram Per Square Centimetre | 98,066.5 |

Torr | Torr | 133.322368421053 … |

mTorr | Millitorr | 0.133322368421053 … |

atm | Standard Atmosphere | 101,325 |

at | Technical Atmosphere | 98,066.5 |

dyn/cm², dyne/cm² | Dyne Per Square Centimetre | 0.1 |

oz/in², ozf/in² | Ounce Per Square Inch | 430.922330823023 … |

tsi, tfsi (uk, long) | Ton Per Square Inch (uk, long) | 15,444,256.3366971 … |

tsi, tfsi (usa, short) | Ton Per Square Inch (usa, short) | 13,789,514.5863367 … |

tsf, tfsf (usa, short) | Ton Per Square Foot (usa, short) | 95,760.5179606717 … |

psf, pfsf | Pounds Force Per Square Foot | 47.8802589803358 … |

g/cm², gf/cm² | Gram Per Square Centimetre | 98.0665 |

*N.B. Numbers which include […] on the end are rounded.*

#### Manometric Conversion Factors

The following units are known as manometric pressure units and are derived from the pressure exerted by a column of liquid under the acceleration of earth’s gravity. Each manometric pressure unit is shown with its equivalent value converted into pascals (Pa). The pascal is the SI unit for measuring pressure.

Since the pressure of the fluid column can vary with changes in liquid density and local gravity it is important to quantify these factors when using these units. The physical assumptions that these conversions factors are based can be found at the bottom of this section.

The use of manometric units is discouraged by national standard organisations because they do not precisely represent the true pressure and there are differing conventions used for the temperature and density of the liquid which can lead to variation in accuracy.

Symbol | Name | Pascals Value |
---|---|---|

mmH2O, mmWG, mmWC | Millimetres of Water | 9.80665 |

cmH2O, cmWG, cmWC | Centimetres of Water | 98.0665 |

mH2O, mWG, mWC | Metres of Water | 9,806.65 |

inH2O, inWG, inWC | Inches of Water | 249.08891 |

ftH2O, ftWG, ftWC | Feet of Water | 2,989.06692 |

mmHg | Millimetres of Mercury | 133.322387415 |

cmHg | Centimetres of Mercury | 1,333.22387415 |

inHg | Inches of Mercury | 3,386.388640341 |

µHg, µmHg | Microns of Mercury | 0.133322387415 |

The above manometric pressure units assume the following in their derivation and although they are not physical constants they have been accepted as popular conventions and are used universally:

- Standard acceleration due to gravity of 9.80665 m/s²
- Density of pure water at 4 deg C is 1000 kg/m³
- Density of mercury at 0 deg C is 13,595.1 kg/m³

#### Pascal SI Metric Prefix Pressure Units

These pressure units belong to the SI measurement system where the pascal is derived from the SI units by the following formulas: 1 kg·m^{-1}·s^{-2} ⇒ 1 N·m^{-2} ⇒ 1 Pa.

- yoctopascal (yPa) – 1 x 10
^{-24}Pa - zeptopascal (zPa) – 1 x 10
^{-21}Pa - attopascal (aPa) – 1 x 10
^{-18}Pa - femtopascal (fPa) – 1 x 10
^{-15}Pa - picopascal (pPa) – 1 x 10
^{-12}Pa - nanopascal (nPa) – 1 x 10
^{-9}Pa - micropascal (µPa) – 0.000001 Pa
- millipascal (mPa) – 0.001 Pa
- centipascal (cPa) – 0.01 Pa
- decipascal (dPa) – 0.1 Pa
- pascal (Pa) – 1 Pa
- decapascal (daPa) – 10 Pa
- hectopascal (hPa) – 100 Pa
- kilopascal (kPa) – 1,000 Pa
- megapascal (MPa) – 1,000,000 Pa
- gigapascal (GPa) – 1 x 10
^{+9}Pa - terapascal (TPa) – 1 x 10
^{+12}Pa - petapascal (PPa) – 1 x 10
^{+15}Pa - exapascal (EPa) – 1 x 10
^{+18}Pa - zettapascal (ZPa) – 1 x 10
^{+21}Pa - yottapascal (YPa) – 1 x 10
^{+24}Pa

#### Bar Metric Prefix Pressure Units

These pressure units which belong to the metric unit system where the bar is defined as being exactly equal to 100,000 pascals.

- yoctobar (ybar) – 1 x 10
^{-19}Pa - zeptobar (zbar) – 1 x 10
^{-16}Pa - attobar (abar) – 1 x 10
^{-13}Pa - femtobar (fbar) – 1 x 10
^{-10}Pa - picobar (pbar) – 1 x 10
^{-7}Pa - nanobar (nbar) – 1 x 10
^{-4}Pa - microbar (µbar) – 0.1 Pa
- millibar (mbar) – 100 Pa
- centibar (cbar) – 1,000 Pa
- decibar (dbar) – 10,000 Pa
- bar (bar) – 100,000 Pa
- decabar (dabar) – 1,000,000 Pa
- hectobar (hbar) – 10,000,000 Pa
- kilobar (kbar) – 1 x 10
^{+8}Pa - megabar (Mbar) – 1 x 10
^{+11}Pa - gigabar (Gbar) – 1 x 10
^{+14}Pa - terabar (Tbar) – 1 x 10
^{+17}Pa - petabar (Pbar) – 1 x 10
^{+20}Pa - exabar (Ebar) – 1 x 10
^{+23}Pa - zettabar (Zbar) – 1 x 10
^{+26}Pa - yottabar (Ybar) – 1 x 10
^{+29}Pa

#### Torr Metric Prefix Pressure Units

These pressure units are defined as being exactly equal to 1/760 of one standard atmosphere (101,325 Pa), which can be easily incorporated into calculations simply as 101325/760 Pa which is approximately equal to 133.322 pascals.

- yoctotorr (yTorr) – 1.33322368421053 x 10
^{-22}Pa - zeptotorr (zTorr) – 1.33322368421053 x 10
^{-19}Pa - attotorr (aTorr) – 1.33322368421053 x 10
^{-16}Pa - femtotorr (fTorr) – 1.33322368421053 x 10
^{-13}Pa - picotorr (pTorr) – 1.33322368421053 x 10
^{-10}Pa - nanotorr (nTorr) – 1.33322368421053 x 10
^{-7}Pa - microtorr (µTorr) – 1.33322368421053 x 10
^{-4}Pa - millitorr (mTorr) – 0.133322368421053 Pa
- centitorr (cTorr) – 1.33322368421053 Pa
- decitorr (dTorr) – 13.3322368421053 Pa
- torr (Torr) – 133.322368421053… Pa
- decatorr (daTorr) – 1,333.22368421053 Pa
- hectotorr (hTorr) – 13,332.2368421053 Pa
- kilotorr (kTorr) – 1.33322368421053 x 10
^{+5}Pa - megatorr (MTorr) – 1.33322368421053 x 10
^{+8}Pa - gigatorr (GTorr) – 1.33322368421053 x 10
^{+11}Pa - teratorr (TTorr) – 1.33322368421053 x 10
^{+14}Pa - petatorr (PTorr) – 1.33322368421053 x 10
^{+17}Pa - exatorr (ETorr) – 1.33322368421053 x 10
^{+20}Pa - zettatorr (ZTorr) – 1.33322368421053 x 10
^{+23}Pa - yottatorr (YTorr) – 1.33322368421053 x 10
^{+26}Pa

### Unit Groups

Many units have a similar application or derivation, the use of each varies depending on country, industry and pressure value

#### Units derived from ‘pascal’ the SI unit for pressure

#### Force related pressure units

- N/m²
- dyn/cm², dyne/cm², dynes/cm², d/cm²
- kg/cm², kgf/cm²
- g/cm², gf/cm²
- psi, pfsi, lb/in², lbf/in²
- oz/in², ozf/in²
- tsi (uk, long), tfsi (uk, long)
- tsi (usa, short), tfsi (usa, short)
- tsf (usa, short), tfsf (usa, short)
- psf, pfsf

#### Water related pressure units

- mm H2O, mm WG, mm WC
- cm H2O, cm WG, cm WC
- m H2O, m WG, m WC
- in H2O, in WG, in WC, “H2O, “WG, “WC
- ft H2O, ft WG, ft WC, ‘H2O, ‘WG, ‘WC