Kilopascals to psi:
multiply by 0.145

How many psi are in a kilopascal?

One kilopascal equals 0.1450377377 psi. The kilopascal is the metric (SI) unit commonly used for tyres, compressed air and weather, while psi, pounds per square inch, is the customary unit in the United States.

A kilopascal is one thousand pascals, and a pascal is one newton per square metre. That makes the kPa a small unit of pressure, so you need roughly 6.9 kPa to equal a single psi.

The kPa to psi formula

A second example goes back to kPa. A US bicycle tyre rated at 35 psi is 35 × 6.894757293 = 241.3165 kPa, so a metric pump should read about 241 kPa.

Chart: kPa to psi

To use the chart for other values, scale a row. For 750 kPa add the 500 and 250 rows: 72.51886887 + 36.25943443 = 108.7783033 psi.

Where kPa to psi is used

• Car tyres: manuals and placards outside the US give kPa or bar, while many pumps in the US show psi.
• Compressed air tools: a workshop compressor in psi must match a tool rated in kPa.
• Water pressure: mains pressure of 300 kPa is about 43.5 psi, which matters for hoses, showers and irrigation.
• Weather and altitude: air pressure is quoted in kPa or hPa in many countries.

Quick estimates for kPa to psi

You can estimate a kPa to psi conversion in your head, which is useful at a petrol station or a bike shop. Divide the kPa figure by 7 for a close answer, because 1 psi is 6.89 kPa, which is just under 7.

• 200 kPa divided by 7 is about 28.6 psi. The exact figure is 29.00755 psi.
• 300 kPa divided by 7 is about 42.9 psi. The exact figure is 43.51132 psi.
• 100 kPa is about 14.5 psi, and that is close to normal air pressure at sea level, which is 101.325 kPa or 14.7 psi.

The shortcut slightly underestimates because 7 is bigger than 6.89, so nudge the answer up by about 1.5 percent. For anything safety related, such as a tyre or a pressure vessel, use the exact converter or the figure printed on the equipment.

Common mistakes with kPa and psi

• Confusing kPa with bar. One bar is 100 kPa, so 2.2 bar is 220 kPa, and mixing them gives a tenfold or hundredfold error.
• Mixing up kPa and MPa. One MPa is 1,000 kPa, so a figure that looks 1,000 times too big or small is probably a prefix mistake.
• Forgetting gauge versus absolute pressure. Tyre gauges show the pressure above the surrounding air, which is about 101.3 kPa at sea level.
• Using psi as if it were a metric unit. Psi is pounds per square inch, so mixing it with pascals needs a proper conversion.