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Pressure

Kilopascals to psi

1 kPa = 0.145038 psi

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One kilopascal is 0.1450377377 psi, so a psi is 6.894757293 kPa. The kilopascal is the SI-correct unit that the bar is usually used instead of, and it appears wherever a specification has been written strictly.

About the units

The pascal is the SI unit of pressure: one newton per square metre. It is an inconveniently small unit — atmospheric pressure is about 101,325 Pa — so practical work uses kilopascals or, in meteorology, hectopascals. The kilopascal is exactly one hundredth of a bar, which makes conversion between them trivial and is the reason the bar persists despite not being SI. The psi is defined from the pound-force and the square inch. Because pound-force depends on standard gravity, which was fixed at exactly 9.80665 m/s² in 1901, the psi is exactly convertible to pascals with no measurement involved.

The exact factor

One psi is exactly 6,894.757293168361 Pa, so 6.894757293168361 kPa. The reciprocal gives 0.145037737730209 psi per kPa. Two anchors worth carrying: 100 kPa is 14.5 psi and is also almost exactly one atmosphere, and 700 kPa — a common industrial supply pressure — is 101.5 psi. Note that gauge and absolute pressure differ by one atmosphere: a tyre at 220 kPa gauge is at about 321 kPa absolute, and specifications that omit which they mean are a recurring source of error.

Where you meet this conversion

Australian, Canadian and New Zealand tyre placards use kPa where European ones use bar, so the same car sold in different markets carries different numbers for the same pressure. Engineering specifications written to SI use kPa or MPa throughout. Weather reporting uses hectopascals, which are a tenth of a kilopascal. Medical ventilator settings, vacuum systems and building services all use kilopascals in metric documentation, while American equipment for the same jobs is marked in psi.

Common values

Value (kPa) Converted (psi)
1 0.145038
2 0.290075
5 0.725189
10 1.45038
25 3.62594
50 7.25189
100 14.5038
500 72.5189
1 000 145.038

Values are rounded for reading. The converter above keeps full precision.

The other way around

1 psi = 6.89476 kPa

Psi to kilopascals multiplies by 6.895. For quick work, multiplying psi by 7 overestimates by 1.5 per cent, which is close enough to sanity-check a gauge reading but not to set a relief valve.

Value (psi) Converted (kPa)
1 6.89476
2 13.7895
5 34.4738
10 68.9476
25 172.369
50 344.738
100 689.476
500 3 447.38
1 000 6 894.76

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