Megapascals to Inches Of Mercury (MPa to inHg)

1 megapascal equals 295.299833 inches of mercury (rounded).

How to convert megapascals to inches of mercury

To convert megapascals to inches of mercury, multiply the number of megapascals by 295.299833. The factor is rounded to 10 significant digits. To go the other way, multiply inches of mercury by 0.00338638864 (rounded).

inches of mercury = megapascals × 295.299833

Example: 10 megapascals = 2,952.99833 inches of mercury.

About these units

Megapascal (MPa)

Metric (SI)Current unit

One million pascals. Used for material strength and hydraulic pressure.

Engineers reach for the megapascal because the pascal is far too small for solid materials. It is the preferred unit in engineering for stiffness and for tensile or compressive strength, and stiffness figures go on to gigapascals: aluminium is given as 69 GPa, structural steel as 200 GPa, and diamond as 1,220 GPa.

Fluid systems live in the same range. One megapascal is 10 bar, so scuba tanks filled to about 200 bar sit at 20 MPa, and fixed industrial hydraulic machinery commonly working at around 300 bar runs at about 30 MPa. A kilobar, used in experimental petrology, is 100 MPa.

For comparison with units from the pounds-and-inches world, one psi is about 6.895 kPa, so a megapascal is about 145 psi.

1 megapascal = 1,000,000 pascals (exactly).

Sources: Wikipedia: Pascal (unit); Wikipedia: Bar (unit); Wikipedia: Pounds per square inch

Inch Of Mercury (inHg)

US & ImperialCurrent unit

About 3,386.39 pascals. US weather reports and aircraft altimeters quote barometric pressure in inches of mercury.

Barometers in the United States still speak in inches. The inch of mercury is the pressure exerted by a 1-inch (25.4 mm) column of mercury under standard gravity, which is a conventional value of about 3,386.389 pascals. Because mercury's density depends on temperature, older literature that used a 60 degrees Fahrenheit basis gives about 3,376.85 pascals instead.

Its modern home is weather and flying. US weather reports quote barometric pressure in inHg, and North America and Japan give altimeter settings in it. Aircraft at higher altitudes set their altimeters to a standard 29.92 inHg, which is where flight levels come from, and that number equals one standard atmosphere.

Mechanics know it from vacuum and boost gauges. Technicians describe refrigerant-system vacuum in inHg, automotive cooling system fill tools typically hold 22 to 27 inHg of vacuum, and railways once used it for vacuum brakes.

1 inch of mercury = 3,386.38864 pascals (approximately).

Sources: Wikipedia: Inch of mercury; Wikipedia: Standard atmosphere (unit); Wikipedia: Atmospheric pressure

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