Kilopascal to PSI Converter
Our free force pressure & torque converter handles kilo pascal psiconverter conversions. See tables, ratios, and examples for quick reference.
Kilopascal to PSI Converter
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Formula: PSI = kPa x 0.145038
Worked example โ 240 kPa = 34.8091 PSI = 2.40 bar
Formula
PSI = kPa x 0.145038
Multiply kilopascals by 0.145038 to get PSI. To convert PSI to kPa, multiply by 6.89476. For bar, divide kPa by 100. For atmospheres, divide kPa by 101.325. For mmHg, multiply kPa by 7.50062.
Worked Examples
Example 1: Converting Tire Pressure
Problem:A tire placard says 240 kPa. What is that in PSI?
Solution:PSI = kPa x 0.145038 PSI = 240 x 0.145038 = 34.8091 PSI bar = 240 / 100 = 2.4000 bar atm = 240 / 101.325 = 2.3686 atm
Result:240 kPa = 34.8091 PSI = 2.40 bar
Example 2: Converting Water Pressure
Problem:A pressure gauge reads 55 PSI. Convert to kilopascals.
Solution:kPa = PSI x 6.89476 kPa = 55 x 6.89476 = 379.2118 kPa bar = 379.2118 / 100 = 3.7921 bar atm = 379.2118 / 101.325 = 3.7425 atm
Result:55 PSI = 379.2118 kPa = 3.79 bar
Frequently Asked Questions
What is the conversion factor from kilopascals to PSI?
One kilopascal equals 0.145038 pounds per square inch (PSI). Conversely, one PSI equals 6.89476 kilopascals. The pascal is the SI unit of pressure defined as one newton per square meter, so a kilopascal is 1,000 pascals. PSI is defined as one pound-force applied over one square inch of area. These conversion factors are exact to six significant figures and are used internationally in engineering, automotive, and industrial applications.
Why do some countries use kPa and others use PSI?
Countries that adopted the metric system use kilopascals as their standard pressure unit because the pascal is the SI unit of pressure. The United States, along with a few other countries still using imperial measurements, primarily uses PSI. In the automotive industry, tire pressure is listed in kPa in most of the world but in PSI in North America. Many pressure gauges are dual-labeled with both units to accommodate international standards and make it easier for users across different regions.
What are common pressure values in kPa and PSI?
Standard atmospheric pressure at sea level is 101.325 kPa or 14.696 PSI. A typical car tire pressure of 32 PSI equals about 220.6 kPa. A bicycle road tire at 100 PSI is approximately 689.5 kPa. Household water pressure usually runs between 275-550 kPa (40-80 PSI). Scuba tanks are filled to about 20,684 kPa (3,000 PSI). These reference values are helpful for quickly checking whether a conversion result is in the right ballpark.
How does kPa relate to other metric pressure units like bar and atmosphere?
One bar equals exactly 100 kPa, making that conversion very simple. One standard atmosphere (atm) equals 101.325 kPa. One megapascal (MPa) equals 1,000 kPa. The hectopascal (hPa), used in meteorology, equals 0.1 kPa. In medical applications, millimeters of mercury (mmHg) are common where 1 kPa equals 7.50062 mmHg. Understanding these relationships helps when working across different fields that prefer different pressure units.
Is gauge pressure different from absolute pressure?
Yes, and this distinction is critical for accurate conversions. Gauge pressure (psig or kPa gauge) measures pressure relative to atmospheric pressure, meaning a reading of zero indicates atmospheric pressure. Absolute pressure (psia or kPa absolute) measures from a perfect vacuum, so atmospheric pressure reads as 101.325 kPa or 14.696 psi. When converting between kPa and PSI, ensure both values use the same reference point. Tire pressure gauges, for example, always show gauge pressure.
How are the pascal and the PSI defined?
The pascal is the SI unit of pressure, defined as one newton per square metre, which in SI base units is kilogram per metre per second squared. A kilopascal is 1,000 pascals. PSI is pounds-force per square inch, built from the pound-force and the inch rather than from SI. Because the pound-force and the inch both have exact SI definitions, the conversion is exact in principle: 1 psi = 6.894757 kPa, and 1 kPa = 0.1450377 psi. The pascal alone is inconveniently small for engineering, which is why kPa, bar and MPa are used instead.
How do you convert kilopascals into a column of water or mercury?
Pressure from a fluid column is density times gravity times height, so height equals pressure divided by density times gravity. With water at 1,000 kg per cubic metre and standard gravity of 9.80665 metres per second squared, one kilopascal supports 1,000 / (1,000 x 9.80665) = 0.10197 metres, so 1 kPa is about 102 millimetres of water. Mercury is roughly 13.6 times denser, giving 1 kPa = 7.50062 mmHg, or torr. These equivalents appear on manometers and in HVAC duct static pressure, and they let you sanity-check a converted value physically.
Why does the pressure in a sealed tyre or vessel change with temperature?
For a fixed volume of gas, absolute pressure is proportional to absolute temperature, so cooling reduces pressure and heating raises it. The key point is that the proportion applies to absolute pressure, not to the gauge reading. A tyre at 220 kPa gauge is about 321 kPa absolute; cooling from 20 degrees Celsius to 10 degrees is a drop from 293 K to 283 K, or 3.4 percent, so absolute pressure falls by about 11 kPa and the gauge reads roughly 209 kPa, some 1.6 psi lower. This is why pressures should be checked cold and against a stated reference temperature.
Why are vacuum measurements expressed as absolute pressure rather than gauge?
Below atmospheric pressure a gauge reading goes negative, and its meaning then depends on the local barometric pressure that day and at that altitude, which makes it useless for comparing results. Absolute pressure measures from a perfect vacuum, so a reading is unambiguous: 20 kPa absolute is 20 kPa absolute anywhere. Vacuum work also spans many orders of magnitude, so the millibar, the torr and the pascal itself are used rather than kPa or PSI, letting the scale run smoothly down toward zero instead of bottoming out at an arbitrary reference.
Does converting kPa to PSI make a gauge reading more precise?
No. The conversion factor is exact, so it neither adds nor removes information; accuracy is fixed by the instrument. Mechanical gauges are typically specified as a percentage of full scale, so a gauge with a 0 to 1,000 kPa span and a 1 percent class can be off by 10 kPa anywhere on the dial, including near the bottom where that is a large fraction of the reading. Reporting a converted value to five decimals therefore implies precision the gauge never had; round to match its resolution.
References
Background & Theory
1 kilopascal = 0.145037738 psi, and 1 psi = 6.89475729317 kilopascals exactly. The pascal is the coherent SI pressure unit - one newton per square metre - and the psi is defined from the exact pound-force and the exact square inch, so the kPa figure terminates.
Conversion reference table
| Conversion | Equivalent | Exact or rounded? |
|---|---|---|
| 1 psi | 6.89475729317 kilopascals | Exact by definition |
| 1 kilopascal | 0.145037738 psi | Derived, rounded |
| 101.325 kilopascals | 1 atmosphere = 14.6959488 psi | Exact / derived |
| 100 kilopascals | 1 bar = 14.5037738 psi | Exact / derived |
| 220 kilopascals (typical tyre) | 31.9 psi | Derived |
| 1 megapascal | 145.037738 psi | Derived, rounded |
Vehicle tyre placards outside the United States are usually printed in kPa in round numbers - 220, 240, 260 - which convert to the untidy 31.9, 34.8 and 37.7 psi, so a US gauge set to a "round" 32 psi is close but not identical to the placard. Engineering drawings normally use megapascals for material strength, where 1 MPa is 145.04 psi, and one newton per square millimetre is exactly 1 MPa.
Reviewed for accuracy by Manoj Kumar, Mathematics Educator ยท Editorial policy
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