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Pascal to PSI Converter

Use this free Pascal to PSI converter to change a pressure in pascals into pounds per square inch (PSI), or to change PSI back into pascals. It works in both directions, accepts kilopascals, megapascals, bar, atmospheres and millimetres of mercury as well, and shows every equivalent value at once, so one conversion answers every version of the same question.

How it works

Pressure is force spread over an area. The pascal is the metric unit of pressure: one pascal is one newton of force pushing on one square metre. It is named after Blaise Pascal, a seventeenth-century French mathematician and physicist. Because one pascal is a tiny amount of pressure — roughly the weight of a small coin resting on a table — everyday pressures are usually written in kilopascals, where one kilopascal is one thousand pascals, or in megapascals, where one megapascal is one million pascals.

PSI stands for pounds per square inch. It is the pressure unit used most often in everyday life in countries that use imperial units: tire pressures, air compressor settings, water pressure in a home, and bicycle pump readings are all usually given in PSI. One PSI is the pressure of one pound of force spread over one square inch. The exact relationship between the two units is fixed: one PSI equals 6,894.757 pascals, and one pascal equals 0.0001450377 PSI.

To convert pascals to PSI, divide the pascal value by 6,894.757. To convert PSI to pascals, multiply the PSI value by the same number. When the input is in kilopascals, first multiply by 1,000 to get pascals, then divide; when it is in megapascals, multiply by 1,000,000 first. One bar equals 100,000 pascals, one standard atmosphere equals 101,325 pascals, and one millimetre of mercury equals 133.322 pascals. The converter above applies these exact factors and then rounds the display to four decimal places for PSI and a sensible number of decimals for the other units, so the arithmetic is the same arithmetic a reference table would give.

It helps to know which unit a reading is probably in before converting. A car tire at 220 kPa is a normal pressure; written as 220,000 pascals it looks enormous, and written as 31.91 PSI it looks familiar. A weather report giving 101.3 kPa is describing ordinary sea-level air pressure, not a storm. A bicycle tire at 65 PSI is about 448 kPa. If a number looks impossibly large or impossibly small after conversion, the usual cause is a mix-up between pascals and kilopascals — a factor of one thousand — so check the unit first.

Common pressure values

The table below lists pressures you are likely to meet in real life, in both pascals and PSI. Atmospheric pressure is the pressure of the air around us at sea level. A car tire, a bicycle tire, a home water supply, and a scuba tank span a wide range, which is why the same table needs both small and large numbers.

Notice how the scuba tank, at 3,000 PSI, is about two hundred times atmospheric pressure, while a car tire at about 32 PSI is only a little over twice atmospheric pressure. That gap is the reason pressure vessels such as scuba tanks and gas cylinders are built and tested so much more heavily than a tire, and why their pressures are usually discussed in PSI or bar rather than in pascals, where the numbers would run into the millions.

Worked example

A driver checks a tire pressure gauge that reads in kilopascals and sees 220 kPa. The car manual gives the recommended pressure in PSI, so the driver needs to convert. Start by turning kilopascals into pascals: 220 kPa times 1,000 equals 220,000 pascals. Then divide by the conversion factor: 220,000 divided by 6,894.757 equals 31.9083. The tire is therefore at 31.91 PSI, which sits inside the usual 30 to 35 PSI range for a passenger car, so no air needs adding.

Now try the reverse direction with the converter. Type 30 into the PSI field and switch the direction to PSI to pascals. The tool multiplies 30 by 6,894.757 and gives 206,842.7 pascals, or 206.84 kPa. That matches the low end of the car tire range in the table above: 30 PSI and 207 kPa describe the same pressure. As a second check, enter the standard atmospheric pressure, 101,325 pascals. Dividing 101,325 by 6,894.757 gives 14.6959 PSI, the figure shown in the result box when the page first loads.

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