Convert pound-force per square inch to megapascal.

Convert pound-force per square inch (psi) to megapascal (MPa). This is a fixed-ratio conversion — multiply the input by the factor below.

Formula

MPa = psi × 0.00689476

Reference values

Things to watch for

• psi can be gauge (psig, above atmospheric) or absolute (psia). At sea level, psia = psig + 14.7. Specify which.
• 1 atm = 14.696 psi = 1.01325 bar = 101.325 kPa = 760 mmHg. These are all defined exactly.
• For tire pressure use psi or bar; for weather mbar/hPa; for vacuum work torr or Pa; for industrial fluid power MPa.

What is a pounds per square inch?

One psi equals about 6,894.76 pascals — the pressure of one pound-force applied over one square inch. US tire pressure (typically 30-35 psi for cars), hydraulics, and engineering specifications.

What is a megapascal?

One megapascal equals 1,000,000 pascals or 1,000 kilopascals. Material strength (yield stress, ultimate tensile), high-pressure systems, and hydraulics.

How big is one psi in real terms?

These anchors can be useful when sizing up a value. 3000 psi is a SCUBA tank; 1 psi is a soft pillow pressed against your hand; and 14.7 psi is atmospheric pressure at sea level.

How to convert pounds per square inch to megapascal

To convert a value from pounds per square inch (psi) to megapascal (MPa), apply the conversion factor shown in the formula above. The calculation is the same whether you do it by hand, in a spreadsheet, or with the live converter on this page.

Steps:

1. Take your input value in psi.
2. Apply the formula MPa = psi × 0.00689476.
3. The result is your value in MPa.

For repeated calculations, save the formula in a spreadsheet or use the live converter at the top of this page — it handles the math automatically and displays the result as you type.

Frequently asked questions

How do I convert psi to MPa?

Apply the formula psi → MPa shown above, or just type your value into the converter at the top of this page. The result updates instantly.

Which is bigger, psi or MPa?

This depends on the conversion ratio in the formula. If the factor multiplied by your value gives a larger number, then MPa is the smaller unit (so it takes more of them to express the same quantity). If the result is smaller, then MPa is the larger unit.

When would I use psi versus MPa?

Both units measure pressure, so the choice depends on context. Pounds per square inch is typically used for tires, weather, hydraulics, and material strength; megapascal similarly. Most professional fields standardize on one or the other based on regional conventions or technical tradition.

How precise is this psi to MPa conversion?

The conversion factor shown is the internationally defined exact value (or the best-published approximation if the relationship is irrational, like degrees-to-radians). The live converter on this page uses double-precision floating-point math, accurate to about 15 significant digits — far beyond any practical engineering need.

Is the conversion ratio exact, or an approximation?

Most unit conversions between SI metric units, and between SI and US customary units, have been formally defined as exact values since the 1959 international yard-pound agreement and subsequent SI redefinitions. Exceptions are unit pairs that involve irrational numbers (radians, e.g.) or empirical conversions (like food calories, which depend on temperature). When in doubt, consult the formula at the top of this page.

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See also