Convert Inch of Mercury to Megapascal (inHg → MPa)
The inch of mercury is the American aviation standard for altimeter settings and historic barometer readings.
Inch of Mercury to Megapascal Conversion Table
10 common values| Inch of Mercury | Megapascal |
|---|---|
| 1 inHg | 0.003386 MPa |
| 5 inHg | 0.016932 MPa |
| 10 inHg | 0.033864 MPa |
| 25 inHg | 0.08466 MPa |
| 50 inHg | 0.169319 MPa |
| 100 inHg | 0.338639 MPa |
| 200 inHg | 0.677278 MPa |
| 500 inHg | 1.693195 MPa |
| 1,000 inHg | 3.386389 MPa |
| 5,000 inHg | 16.931945 MPa |
How to Convert Inch of Mercury to Megapascal Manually
Step by StepConverting inches of mercury to megapascals is straightforward: multiply by the conversion factor. Follow these three steps to do it by hand or in your head.
- 1Take your value in inches of mercuryStart with the number of inches of mercury (inHg) you want to convert.
- 2Multiply by 0.003386The conversion factor from inHg to MPa is 0.003386. Multiply your value by this number.
- 3Read the result in megapascalsThe result is your value in megapascals (MPa).
Formula
Multiply the value in inches of mercury by 0.003386. For the reverse direction, multiply by 295.2998.
MPa = inHg × 0.003386inHg = MPa × 295.2998Tips
Use these in everyday conversions- 1 inHg ≈ 3386 Pa ≈ 33.86 mbar.
- 29.92 inHg = 1013.25 mbar = 1 atm.
- US pilots use inHg; European pilots use hPa (mbar).
Common Mistakes
Avoid these- Confusing inHg with mmHg — factor of 25.4.
- Mixing US and European altimeter units on a single flight plan.
- Using inHg on scientific papers — prefer Pa.
About Inch of Mercury and Megapascal
What is the Inch of Mercury?
The inch of mercury equals exactly 25.4 mmHg (or about 3,386.4 pascals) and is the American aviation standard for altimeter settings and historic barometer readings. Pilots set their altimeters to the local atmospheric pressure in inHg before takeoff and landing — standard 'sea-level pressure' is 29.92 inHg. American weather reports historically used inHg before transitioning to millibars/hPa, and home barometers in the US still display inHg. The unit relates to the mmHg (25.4 mmHg = 1 inHg), the millibar (1 inHg ≈ 33.864 mbar), the kilopascal (1 inHg ≈ 3.386 kPa), and the psi (1 inHg ≈ 0.491 psi). Aviation's continued use of inHg in the United States reflects regulatory tradition rather than scientific advantage; international ATC outside the US uses hectopascals.
- US aviation altimeter QNH settings
- US residential barometers
- US weather forecasts (older)
Sea-level standard: 29.92 inHg. Mountain pass at 3000 m: ~21 inHg. US aviation QNH given in inHg.
What is the Megapascal?
The megapascal equals 1,000,000 pascals (or 10 bar) and is the engineering high-pressure unit used in hydraulics, materials testing, and construction. Concrete compressive strength is rated in MPa (typical residential concrete is 20–35 MPa, structural concrete 35–70 MPa, high-strength up to 140 MPa), and steel yield strengths are 250–700 MPa for structural grades. Hydraulic systems operate at 10–70 MPa, and high-pressure-water-jet cutting reaches 400 MPa. The megapascal is dimensionally identical to N/mm² (newtons per square millimeter), making it natural for engineering calculations involving small areas. Earth's mantle pressure reaches gigapascals (1 GPa = 1,000 MPa). The MPa relates to the pascal (10⁶ Pa = 1 MPa), the bar (10 bar = 1 MPa), the psi (1 MPa ≈ 145.04 psi), and the atmosphere (1 MPa ≈ 9.87 atm). It is the standard unit in modern engineering specifications worldwide.
- Hydraulic system pressures
- Concrete and steel strength specifications
- High-pressure industrial processes
Concrete compressive strength: 20–60 MPa. Hydraulic press: 30–70 MPa. Steel yield strength: 250+ MPa.