UnitsConverter

Inch of Mercury to Megapascal Converter

Convert inches of mercury to megapascals with our free online pressure converter.

Quick Answer

1 Inch of Mercury = 0.003386 megapascals

Formula: Inch of Mercury × conversion factor = Megapascal

Use the calculator below for instant, accurate conversions.

Our Accuracy Guarantee

All conversion formulas on UnitsConverter.io have been verified against NIST (National Institute of Standards and Technology) guidelines and international SI standards. Our calculations are accurate to 10 decimal places for standard conversions and use arbitrary precision arithmetic for astronomical units.

Last verified: February 2026Reviewed by: Sam Mathew, Software Engineer

Inch of Mercury to Megapascal Calculator

How to Use the Inch of Mercury to Megapascal Calculator:

  1. Enter the value you want to convert in the 'From' field (Inch of Mercury).
  2. The converted value in Megapascal will appear automatically in the 'To' field.
  3. Use the dropdown menus to select different units within the Pressure category.
  4. Click the swap button (⇌) to reverse the conversion direction.
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How to Convert Inch of Mercury to Megapascal: Step-by-Step Guide

Converting Inch of Mercury to Megapascal involves multiplying the value by a specific conversion factor, as shown in the formula below.

Formula:

MPa = inHg × 0.00338639

Example Calculation:

1 inHg = 0.003386 MPa

Disclaimer: For Reference Only

These conversion results are provided for informational purposes only. While we strive for accuracy, we make no guarantees regarding the precision of these results, especially for conversions involving extremely large or small numbers which may be subject to the inherent limitations of standard computer floating-point arithmetic.

Not for professional use. Results should be verified before use in any critical application. View our Terms of Service for more information.

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What is a Inch of Mercury and a Megapascal?

1 inHg = 3,386.39 Pa = 3.386 kPa = 33.86 mbar = 33.86 hPa = 0.491 PSI = 0.0334 bar = 0.0334 atm = 25.4 mmHg

Key relationship: 29.92 inHg = 1 atmosphere (exactly)

Origin: Mercury Column

The unit literally measures how high mercury rises:

  • Historical: Barometers invented in 1600s used mercury column
  • Measurement: Mercury rises/falls with atmospheric pressure
  • 1 inHg: Mercury column exactly 1 inch high
  • 29.92 inHg: Mercury rises 29.92 inches at sea level (1 atm)
  • Why mercury?: Highest density liquid (narrow barometer), visible, stable

1 MPa = 1,000,000 Pa = 1,000 kPa = 145.038 PSI = 10 bar = 9.869 atm

Why Megapascal?

MPa is the "sweet spot" for engineering pressures:

  • Pascal is too small: 1 Pa = barely measurable (atmospheric is 101,325 Pa)
  • Kilopascal is too granular: Engineering specs in kPa are 4-5 digit numbers (20,000 kPa for concrete)
  • MPa is optimal: Concrete 20-40 MPa (simple, memorable)
  • Engineering standard: All material specs given in MPa
  • SI-derived: ISO and international standards use MPa

Note: The Inch of Mercury is part of the imperial/US customary system, primarily used in the US, UK, and Canada for everyday measurements. The Megapascal belongs to the imperial/US customary system.

Common Uses and Applications: inches of mercury vs megapascals

Explore the typical applications for both Inch of Mercury (imperial/US) and Megapascal (imperial/US) to understand their common contexts.

Common Uses for inches of mercury

US Weather: Barometric pressure in weather forecasts, NOAA reports - THE US standard. Aviation: Altimeter settings (US standard, some international - critical for flight safety). HVAC: Vacuum measurements, duct pressure, system diagnostics. Historical meteorology: Traditional US measurement since early 1900s.

When to Use megapascals

Materials Engineering: Tensile strength, compressive strength, yield strength - THE standard unit for all material properties. Hydraulics: High-pressure hydraulic systems (construction, manufacturing, heavy equipment). Pressure Vessels: Gas cylinders, boilers, reactors, automotive fuel systems. Geotechnical: Soil bearing capacity, rock strength, foundation design. Aerospace: Structural requirements, component ratings.

Material Strengths (Compressive/Tensile)

Understanding material strength is critical for engineering design:

| Material | Type | Strength (MPa) | Notes | |---|---|---|---| | Styrofoam | Compression | 0.01-0.1 | Very weak, insulation only | | Wood (softwood) | Compression | 20-40 | Pine, spruce, fir typical | | Wood (hardwood) | Compression | 40-60 | Oak, maple stronger | | Brick | Compression | 10-40 | Varies by firing temperature | | Concrete (standard) | Compression | 20-40 | Common 28-day strength | | Concrete (high-strength) | Compression | 50-100 | Pre-stressed applications | | Granite | Compression | 100-250 | Very strong, suitable for columns | | Aluminum alloy (6061) | Tensile | 200-300 | Common structural aluminum | | Aluminum alloy (7075) | Tensile | 500-600 | High-strength aerospace | | Steel (structural ASTM A36) | Yield | 250 | Common building steel | | Steel (high-strength ASTM A572) | Yield | 345-450 | Bridge, crane applications | | Steel (ultra-high) | Tensile | 500-1,000 | Special applications | | Steel cable (wire rope) | Tensile | 1,600-2,000 | Elevators, suspension bridges | | Carbon fiber composite | Tensile | 3,000-7,000 | Aerospace, racing | | Kevlar fiber | Tensile | 3,600-3,800 | Armor, protective gear |

Design factor: Actual working stress = material strength ÷ safety factor (typically 2-4)

Hydraulic Systems (High Pressure)

Hydraulic pressure ratings define system capability:

| System Type | Operating Pressure | Peak Pressure | PSI Equivalent | Application | |---|---|---|---|---| | Automotive brake | 10-15 MPa | 20 MPa | 1,500-2,900 PSI | Car braking force | | Automobile power steering | 10-15 MPa | 20 MPa | 1,500-2,900 PSI | Steering assist | | Construction excavator | 20-35 MPa | 40 MPa | 2,900-5,800 PSI | Digging bucket | | Backhoe | 25-30 MPa | 35 MPa | 3,625-5,075 PSI | Heavy lifting | | Dump truck bed | 20-25 MPa | 30 MPa | 2,900-4,350 PSI | Lifting load | | Industrial press | 20-40 MPa | 50 MPa | 2,900-7,250 PSI | Metal forming | | Hydraulic jack | 50-70 MPa | 80 MPa | 7,250-11,600 PSI | Lifting capability | | Water jet cutter | 200-400 MPa | 450 MPa | 29,000-65,000 PSI | Material cutting | | Oil well pump | 100-200 MPa | 250 MPa | 14,500-36,250 PSI | Deep well pressure |

Pressure Vessels & Storage

Pressure ratings determine safe working limits:

| Vessel Type | Typical Pressure | Material | Working PSIG | |---|---|---|---| | Compressed air tank | 0.8-1.0 MPa | Steel | 116-145 PSI | | Propane BBQ tank | 1.5-2.0 MPa | Steel | 218-290 PSI | | Scuba tank (full) | 20-30 MPa | Aluminum/Steel | 3,000-4,350 PSI | | Natural gas vehicle | 20-25 MPa | Composite | 3,000-3,625 PSI | | Hydrogen fuel cell | 35-70 MPa | Carbon fiber | 5,000-10,000 PSI | | Industrial gas cylinder | 15-20 MPa | Steel | 2,175-2,900 PSI | | Medical oxygen | 13.8-15 MPa | Aluminum | 2,000-2,175 PSI | | Nitrogen (instrument) | 10-13.8 MPa | Steel | 1,450-2,000 PSI |

Safety factor: Pressure vessels typically designed with 4:1 to 6:1 safety margin

Geotechnical Engineering (Soil/Rock)

Foundation and excavation design based on pressure ratings:

| Material/Condition | Bearing Capacity | Suitable For | Notes | |---|---|---|---| | Soft clay | 0.05-0.2 MPa | Temporary structures | High settlement risk | | Medium clay | 0.1-0.3 MPa | Single story | Careful design needed | | Stiff clay | 0.3-0.5 MPa | Multi-story buildings | Good load capacity | | Dense sand | 0.3-0.6 MPa | Foundation base | Excellent for building | | Gravel/sand mixture | 0.6-1.0 MPa | Heavy structures | Very good bearing | | Soft rock (shale) | 1-10 MPa | Bridge supports | Rock analysis needed | | Medium rock | 10-50 MPa | Tall buildings | High capacity | | Hard rock (granite) | 50-100+ MPa | Largest structures | Excellent foundation |

Design process: Site investigation → soil tests → pressure capacity → foundation design

Additional Unit Information

About Inch of Mercury (inHg)

How do I convert inHg to PSI?

Formula: PSI = inHg × 0.491154

Examples:

  • 29.92 inHg = 14.7 PSI (sea level)
  • 30 inHg = 14.74 PSI
  • 28 inHg = 13.75 PSI (hurricane)
  • 25 inHg = 12.28 PSI
  • 20 inHg = 9.82 PSI

inHg to PSI converter →

How many inHg is normal atmospheric pressure?

Standard sea level = 29.92 inHg (exactly 1 atmosphere)

Typical weather range: 29.4-30.5 inHg

Pressure variations:

  • High pressure: 30.2-30.5 inHg (fair weather)
  • Normal: 29.8-30.2 inHg
  • Low pressure: 29.4-29.8 inHg (rain likely)
  • Storm: <29.4 inHg

Barometer rising/falling:

  • Rising: Improving weather
  • Steady: Conditions stable
  • Falling: Weather deteriorating

How do I convert inHg to mbar or hPa?

Formula: mbar (or hPa) = inHg × 33.8639

Examples:

  • 29.92 inHg = 1,013.25 mbar = 1,013.25 hPa (standard)
  • 30.0 inHg = 1,016 mbar
  • 29.0 inHg = 982 mbar (low pressure)
  • 28.0 inHg = 948 mbar (hurricane)
  • 31.0 inHg = 1,050 mbar (high pressure)

inHg to mbar converter → inHg to hPa converter →

Why does US use inHg instead of mbar/hPa?

Historical: US adopted imperial/customary units Mercury barometers: Traditionally marked in inches in US Weather tradition: NOAA, Weather Channel use inHg since inception Familiarity: Public knows "normal is about 30 inches" Aviation: US pilots trained with inHg altimeter settings

Rest of world: Uses mbar or hPa (metric standard)

Conversion: 30 inHg ≈ 1,000 mbar (approximately)

Trend: Slow transition—some US reports now show both units

How do I read a mercury barometer in inHg?

How it works: Mercury column rises/falls with atmospheric pressure

Reading:

  • Look at top of mercury meniscus (curved surface)
  • Read scale at eye level to avoid parallax error
  • Scale typically 28-31 inHg range

Interpreting:

  • 30.2-30.5 inHg: High pressure (fair, clear weather)
  • 29.8-30.2 inHg: Normal (stable conditions)
  • 29.4-29.8 inHg: Low pressure (clouds, possible rain)
  • <29.4 inHg: Very low (storm likely)

Trend matters: Falling rapidly = weather worsening; Rising = improving

Adjustment: Correct for altitude (sea level reading)

About Megapascal (MPa)

How do I convert MPa to PSI?

Formula: PSI = MPa × 145.038

Examples:

  • 1 MPa = 145 PSI
  • 10 MPa = 1,450 PSI (car brakes)
  • 20 MPa = 2,900 PSI (hydraulic tools)
  • 30 MPa = 4,350 PSI (scuba tank)
  • 70 MPa = 10,153 PSI (H2 fuel tank)

MPa to PSI converter →

What is concrete strength in MPa?

Residential concrete: 20-32 MPa (2,900-4,650 PSI)

  • Footings/slabs: 20-25 MPa
  • Foundation walls: 25-30 MPa
  • Driveway: 25-32 MPa

Commercial concrete: 30-50 MPa

  • Floors: 30-35 MPa
  • Beams/columns: 35-50 MPa

High-strength: 50-100+ MPa

  • High-rise buildings: 50-80 MPa
  • Bridges: 60-100 MPa
  • Special applications: 100-150 MPa

Conversion: Divide PSI by 145 to get MPa (e.g., 3,000 PSI ≈ 21 MPa)

How do I convert MPa to bar?

Formula: bar = MPa × 10

Examples:

  • 0.1 MPa = 1 bar
  • 1 MPa = 10 bar
  • 2 MPa = 20 bar
  • 10 MPa = 100 bar
  • 20 MPa = 200 bar (scuba tank)

MPa to Bar converter →

What is a typical hydraulic system pressure?

Low pressure: 7-14 MPa (1,000-2,000 PSI)

  • Automotive power steering: 8-12 MPa
  • Light hydraulic lifts: 7-10 MPa

Medium pressure: 14-21 MPa (2,000-3,000 PSI)

  • Construction equipment: 20-25 MPa
  • Agricultural machinery: 14-20 MPa
  • Automotive brakes: 10-15 MPa

High pressure: 21-35 MPa (3,000-5,000 PSI)

  • Industrial presses: 25-35 MPa
  • Heavy construction: 30-35 MPa
  • Excavators: 30-35 MPa

Very high pressure: >35 MPa (>5,000 PSI)

  • Hydraulic jacks: 50-70 MPa
  • Specialized industrial: 70-100 MPa

Why use MPa instead of PSI for material strength?

SI standard: International engineering uses MPa universally Simpler numbers: 400 MPa vs 58,000 PSI Scientific: Consistent with stress calculations (force/area in N/m²) Global: Specifications understood worldwide

Conversion: PSI ÷ 145 ≈ MPa (or PSI × 0.00689 = MPa)

Example: Steel yield strength

  • As MPa: 250-400 MPa (easy)
  • As PSI: 36,000-58,000 PSI (unwieldy)

Conversion Table: Inch of Mercury to Megapascal

Inch of Mercury (inHg)Megapascal (MPa)
0.50.002
10.003
1.50.005
20.007
50.017
100.034
250.085
500.169
1000.339
2500.847
5001.693
1,0003.386

People Also Ask

How do I convert Inch of Mercury to Megapascal?

To convert Inch of Mercury to Megapascal, enter the value in Inch of Mercury in the calculator above. The conversion will happen automatically. Use our free online converter for instant and accurate results. You can also visit our pressure converter page to convert between other units in this category.

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What is the conversion factor from Inch of Mercury to Megapascal?

The conversion factor depends on the specific relationship between Inch of Mercury and Megapascal. You can find the exact conversion formula and factor on this page. Our calculator handles all calculations automatically. See the conversion table above for common values.

Can I convert Megapascal back to Inch of Mercury?

Yes! You can easily convert Megapascal back to Inch of Mercury by using the swap button (⇌) in the calculator above, or by visiting our Megapascal to Inch of Mercury converter page. You can also explore other pressure conversions on our category page.

Learn more →

What are common uses for Inch of Mercury and Megapascal?

Inch of Mercury and Megapascal are both standard units used in pressure measurements. They are commonly used in various applications including engineering, construction, cooking, and scientific research. Browse our pressure converter for more conversion options.

For more pressure conversion questions, visit our FAQ page or explore our conversion guides.

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All Pressure Conversions

Pascal to KilopascalPascal to MegapascalPascal to HectopascalPascal to BarPascal to MillibarPascal to AtmospherePascal to Technical AtmospherePascal to TorrPascal to Millimeter of MercuryPascal to Inch of MercuryPascal to Pound per Square InchPascal to Kilopound per Square InchPascal to Kilogram-force per Square CentimeterPascal to Kilogram-force per Square MeterPascal to Millimeter of Water ColumnPascal to Inch of Water ColumnKilopascal to PascalKilopascal to MegapascalKilopascal to HectopascalKilopascal to BarKilopascal to MillibarKilopascal to AtmosphereKilopascal to Technical AtmosphereKilopascal to TorrKilopascal to Millimeter of MercuryKilopascal to Inch of MercuryKilopascal to Pound per Square InchKilopascal to Kilopound per Square InchKilopascal to Kilogram-force per Square CentimeterKilopascal to Kilogram-force per Square MeterKilopascal to Millimeter of Water ColumnKilopascal to Inch of Water ColumnMegapascal to PascalMegapascal to KilopascalMegapascal to HectopascalMegapascal to BarMegapascal to MillibarMegapascal to AtmosphereMegapascal to Technical AtmosphereMegapascal to TorrMegapascal to Millimeter of MercuryMegapascal to Inch of MercuryMegapascal to Pound per Square InchMegapascal to Kilopound per Square InchMegapascal to Kilogram-force per Square CentimeterMegapascal to Kilogram-force per Square MeterMegapascal to Millimeter of Water ColumnMegapascal to Inch of Water ColumnHectopascal to PascalHectopascal to KilopascalHectopascal to MegapascalHectopascal to BarHectopascal to MillibarHectopascal to AtmosphereHectopascal to Technical AtmosphereHectopascal to TorrHectopascal to Millimeter of MercuryHectopascal to Inch of MercuryHectopascal to Pound per Square InchHectopascal to Kilopound per Square InchHectopascal to Kilogram-force per Square CentimeterHectopascal to Kilogram-force per Square MeterHectopascal to Millimeter of Water ColumnHectopascal to Inch of Water ColumnBar to PascalBar to KilopascalBar to MegapascalBar to HectopascalBar to MillibarBar to AtmosphereBar to Technical AtmosphereBar to TorrBar to Millimeter of MercuryBar to Inch of MercuryBar to Pound per Square InchBar to Kilopound per Square InchBar to Kilogram-force per Square CentimeterBar to Kilogram-force per Square MeterBar to Millimeter of Water ColumnBar to Inch of Water ColumnMillibar to PascalMillibar to KilopascalMillibar to MegapascalMillibar to HectopascalMillibar to BarMillibar to AtmosphereMillibar to Technical AtmosphereMillibar to TorrMillibar to Millimeter of MercuryMillibar to Inch of MercuryMillibar to Pound per Square InchMillibar to Kilopound per Square InchMillibar to Kilogram-force per Square CentimeterMillibar to Kilogram-force per Square MeterMillibar to Millimeter of Water ColumnMillibar to Inch of Water ColumnAtmosphere to PascalAtmosphere to KilopascalAtmosphere to MegapascalAtmosphere to HectopascalAtmosphere to BarAtmosphere to MillibarAtmosphere to Technical AtmosphereAtmosphere to TorrAtmosphere to Millimeter of MercuryAtmosphere to Inch of MercuryAtmosphere to Pound per Square InchAtmosphere to Kilopound per Square InchAtmosphere to Kilogram-force per Square CentimeterAtmosphere to Kilogram-force per Square MeterAtmosphere to Millimeter of Water ColumnAtmosphere to Inch of Water ColumnTechnical Atmosphere to PascalTechnical Atmosphere to KilopascalTechnical Atmosphere to MegapascalTechnical Atmosphere to HectopascalTechnical Atmosphere to BarTechnical Atmosphere to MillibarTechnical Atmosphere to AtmosphereTechnical Atmosphere to Torr

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Verified Against Authority Standards

All conversion formulas have been verified against international standards and authoritative sources to ensure maximum accuracy and reliability.

NIST Reference on Constants, Units and Uncertainty

National Institute of Standards and Technology — Fundamental physical constants and unit conversions

BIPM SI Units

Bureau International des Poids et Mesures — International System of Units (SI) definitions and standards

ISO 80000

International Organization for Standardization — Quantities and units international standards series

Last verified: February 19, 2026