To convert psi to kPa, multiply by 6.8947573. 1 psi equals 6.8947573 kPa, about 6.8% of the atmosphere at sea level.
| psi | kPa |
|---|---|
| 1 psi | 6.8947573 kPa |
| 2 psi | 13.789515 kPa |
| 5 psi | 34.473786 kPa |
| 10 psi | 68.947573 kPa |
| 25 psi | 172.36893 kPa |
| 50 psi | 344.73786 kPa |
| 100 psi | 689.47573 kPa |
| 250 psi | 1,723.6893 kPa |
| 500 psi | 3,447.3786 kPa |
| 1000 psi | 6,894.7573 kPa |
Definition: The pressure created by one pound of force pushing on one square inch of area.
History: PSI grew out of the imperial engineering tradition - especially the steam engine era, when engineers needed a practical way to describe boiler pressure using units they already had (pounds and inches) rather than inventing something new.
Current use: Car and bike tire pressure gauges in the US, home plumbing and HVAC systems, and scuba tank ratings are all commonly quoted in PSI.
Definition: 1,000 pascals - a pascal itself being the pressure from one newton of force spread over one square meter.
History: Named after Blaise Pascal, the French mathematician and philosopher who directed one of history's most famous pressure experiments in 1648: he had his brother-in-law carry a mercury barometer up the Puy de Dôme mountain in central France, proving that atmospheric pressure drops with altitude and settling a fierce scientific debate about whether a true vacuum could exist. Despite the honor, the unit itself wasn't officially named "pascal" until 1971, over 300 years after his death - before that, scientists just wrote "newtons per square meter."
Current use: Weather reports (as kilopascals or the closely related hectopascal), bicycle tire pressure labels, and most engineering specs outside the US.
The factor is 6.89476, which is derived rather than defined, so any decimal you see has been rounded somewhere.
No simple round multiplier is close enough to be useful, so this is one to look up rather than estimate. The exact factor is 6.89476.
The reverse factor is 0.145, so one kPa is that many psi. Two decimal places is plenty for most purposes, and three is more than a tape measure can justify.
To anchor the scale: 1 psi is about 6.89 kPa.