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## Definitions

#### Table of contents

### Pounds per square inch

The pounds per square inch [psi] is a unit of pressure and stress according to the Imperial and US customary systems of units. The unit is derived from the pound-force lb-f, a unit of force and the inch squared, which is a unit of area. The psi unit describes how many pounds (force) are applied on a unit area of square inch. The definition of psi depends on the definitions of the pound-force and the inch units.

Pound-force [lb-f] is defined as the force of gravity on the earth's surface upon a mass equal to one avoirdupois pound. Its equivalence to the respective metric unit, the Newton [N] is: 1 lb-f = 4.4482216152605 N. The above definition depends on the earth's gravity g, which varies from place to place, but is typically standardized as g ≈ 9.80665 m/s^{2} ≈ 32.174049 ft/s^{2}.

Inch [in] is a unit of length for the Imperial and US customary system of units. It was historically conceived as the length of 3 barley-corns. Today, it is defined through the meter [m] SI unit as: 1 in = 0.0254 m (= 2.54 cm = 25.4 mm).

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With the above definitions of lb-f and the inch, relative to their metric equivalents, the conversion rule from psi to KPa becomes:

The relationship between psi and other units of pressure and stress are shown in the following table:

Unit | Symbol | [psi] |
---|---|---|

Kilopascal | KPa | 0.1450377 |

Bar | bar | 14.50377 |

Standard atmosphere | atm | 14.69595 |

Torr | Torr | 0.01933678 |

### Kilopascal

Kilopascal [KPa] is a unit of pressure and stress according to the SI system of units. It is a multiple of Pascal [Pa] (1 KPa = 1000 Pa), which is a derived unit, based on the Newton [N], a unit of force and the meter squared, which is a unit of area. The Pa unit describes how many Newtons (force) are applied on a unit area of square meters.

The relationship between KPa and other units of pressure and stress are shown in the following table:

Unit | Symbol | [kPa] |
---|---|---|

Pascal | Pa | 0.001 |

Megapascal | MPa | 1000 |

Gigapascal | GPa | 1 000 000 |

Pounds per sq. inch | psi | 6.89476 |

Bar | bar | 100 |

Standard atmosphere | atm | 101.325 |

Torr | Torr | 0.1333224 |

### How to convert pounds per sq. inch to kilopascal (psi to KPa)

- Multiply pressure/stress in psi with 6.89476
- The result is the pressure/stress in KPa

For example 10psi is 10x6.89476 ≈ 68.95 KPa

### How to convert kilopascal to pounds per sq. inch (KPa to psi)

- Divide pressure/stress in KPa by 6.89476
- The result is the pressure/stress in psi

For example 100 KPa is 100/6.89476 ≈ 14.50 lb

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### Conversion table from KPa to psi

In the following table some typical pressures in KPa are converted to psi:

[KPa] | [psi] |
---|---|

1 | 0.145 |

5 | 0.7252 |

10 | 1.45 |

20 | 2.901 |

30 | 4.351 |

40 | 5.802 |

50 | 7.252 |

70 | 10.15 |

90 | 13.05 |

100 | 14.5 |

150 | 21.76 |

200 | 29.01 |

300 | 43.51 |

400 | 58.02 |

500 | 72.52 |

600 | 87.02 |

700 | 101.5 |

800 | 116 |

900 | 130.5 |

1000 | 145 |

2000 | 290.1 |

3000 | 435.1 |

### Conversion table from psi to KPa

In the following table some typical pressures in psi are converted to KPa:

[psi] | [KPa] |
---|---|

0.25 | 1.724 |

0.5 | 3.447 |

0.75 | 5.171 |

1 | 6.895 |

2 | 13.79 |

3 | 20.68 |

4 | 27.58 |

5 | 34.47 |

6 | 41.37 |

7 | 48.26 |

8 | 55.16 |

9 | 62.05 |

10 | 68.95 |

12 | 82.74 |

15 | 103.4 |

20 | 137.9 |

25 | 172.4 |

30 | 206.8 |

35 | 241.3 |

40 | 275.8 |

45 | 310.3 |

50 | 344.7 |

60 | 413.7 |

70 | 482.6 |

80 | 551.6 |

90 | 620.5 |

100 | 689.5 |

150 | 1034 |

200 | 1379 |

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