## Definitions

### 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).

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

\[ \begin{split} 1 \,\mathrm{psi} &= \frac{1\,\mathrm{lb-f}}{1\mathrm{in^2}} \\ &= \frac{4.4482216152605 \,\mathrm{N}}{0.0254^2 \,\mathrm{m^2}} \\ &\approx 6894.757293 \,\mathrm{\frac{N}{m^2}} \\ &\approx 6894.757293 \,\mathrm{Pa} \\ &\approx 6.894757293 \,\mathrm{KPa} \\ \end{split} \]

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

### Conversion table from KPa to psi

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

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

1 | |

5 | |

10 | |

20 | |

30 | |

40 | |

50 | |

70 | |

90 | |

100 | |

150 | |

200 | |

300 | |

400 | |

500 | |

600 | |

700 | |

800 | |

900 | |

1000 | |

2000 | |

3000 |

### Conversion table from psi to KPa

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

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

0.25 | |

0.5 | |

0.75 | |

1 | |

2 | |

3 | |

4 | |

5 | |

6 | |

7 | |

8 | |

9 | |

10 | |

12 | |

15 | |

20 | |

25 | |

30 | |

35 | |

40 | |

45 | |

50 | |

60 | |

70 | |

80 | |

90 | |

100 | |

150 | |

200 |