Inches of mercury (inHg) to hectopascals (hPa) conversion

Inches of mercury to hectopascals conversion table

Inches of mercury (inHg)hectopascals (hPa)
00
133.863889532611
267.727779065222
3101.59166859783
4135.45555813044
5169.31944766305
6203.18333719567
7237.04722672828
8270.91111626089
9304.7750057935
10338.63889532611
20677.27779065222
301015.9166859783
401354.5555813044
501693.1944766305
602031.8333719567
702370.4722672828
802709.1111626089
903047.750057935
1003386.3889532611
100033863.889532611

How to convert inches of mercury to hectopascals?

Converting between inches of mercury (inHg) and hectopascals (hPa) involves understanding the relationship between these two units of pressure. Here's a breakdown of the conversion process, some relevant context, and examples.

Understanding the Conversion

Inches of mercury (inHg) is commonly used in the United States to measure atmospheric pressure, particularly in aviation and meteorology. Hectopascals (hPa) are the standard unit of pressure in the International System of Units (SI) and are widely used in meteorology worldwide. One hectopascal is equal to one millibar (mbar).

Conversion Factors

  • 1 inch of mercury (inHg) = 33.86389 hectopascals (hPa)
  • 1 hectopascal (hPa) = 0.02953 inches of mercury (inHg)

These conversion factors are derived from the definition of these units based on standard gravity and temperature (0C0^\circ C).

Step-by-Step Conversion: inHg to hPa

To convert from inches of mercury to hectopascals, multiply the value in inches of mercury by the conversion factor 33.86389.

Formula:

hPa=inHg×33.86389hPa = inHg \times 33.86389

Example: Convert 1 inch of mercury to hectopascals

1 inHg=1×33.86389 hPa=33.86389 hPa1 \text{ inHg} = 1 \times 33.86389 \text{ hPa} = 33.86389 \text{ hPa}

Step-by-Step Conversion: hPa to inHg

To convert from hectopascals to inches of mercury, multiply the value in hectopascals by the conversion factor 0.02953.

Formula:

inHg=hPa×0.02953inHg = hPa \times 0.02953

Example: Convert 1 hectopascal to inches of mercury

1 hPa=1×0.02953 inHg=0.02953 inHg1 \text{ hPa} = 1 \times 0.02953 \text{ inHg} = 0.02953 \text{ inHg}

Historical Context and Interesting Facts

The inch of mercury as a unit is historically linked to the mercury barometer, invented by Evangelista Torricelli in the 17th century. Torricelli, an Italian physicist and mathematician, was the first to create a sustained vacuum and is credited with inventing the barometer. The height of the mercury column in the barometer directly corresponds to the atmospheric pressure. The standard atmosphere (1 atm) is defined as 29.9213 inches of mercury or 1013.25 hPa. NIST - Pressure Units

Real-World Examples and Conversions

Here are some common pressure values converted between inches of mercury and hectopascals:

  • Standard Atmospheric Pressure:
    • 29.92 inHg1013.25 hPa29.92 \text{ inHg} \approx 1013.25 \text{ hPa}
  • High Pressure System (e.g., in weather reports):
    • 30.50 inHg1032.84 hPa30.50 \text{ inHg} \approx 1032.84 \text{ hPa}
  • Low Pressure System (e.g., in weather reports):
    • 29.50 inHg999.00 hPa29.50 \text{ inHg} \approx 999.00 \text{ hPa}
  • Typical tire pressure (cold):
    • If you see a pressure increase of 4 psi4 \text{ psi} that is equivalent to 8.15 inHg8.15 \text{ inHg} or 276 hPa276 \text{ hPa}

These conversions are useful in various applications, from weather forecasting to aviation, ensuring accurate readings and interpretations across different measurement systems.

See below section for step by step unit conversion with formulas and explanations. Please refer to the table below for a list of all the hectopascals to other unit conversions.

What is Inches of mercury?

The "inches of mercury" (inHg) is a unit of pressure commonly used in the United States. It's based on the height of a column of mercury that the given pressure will support. This unit is frequently used in aviation, meteorology, and vacuum applications.

Definition and Formation

Inches of mercury is a manometric unit of pressure. It represents the pressure exerted by a one-inch column of mercury at a standard temperature (usually 0°C or 32°F) under standard gravity.

The basic principle is that atmospheric pressure can support a certain height of a mercury column in a barometer. Higher atmospheric pressure corresponds to a higher mercury column, and vice versa. Therefore, the height of this column, measured in inches, serves as a direct indication of the pressure.

Formula and Conversion

Here's how inches of mercury relates to other pressure units:

  • 1 inHg = 3386.39 Pascals (Pa)
  • 1 inHg = 33.8639 millibars (mbar)
  • 1 inHg = 25.4 millimeters of mercury (mmHg)
  • 1 inHg ≈ 0.0334211 atmosphere (atm)
  • 1 inHg ≈ 0.491154 pounds per square inch (psi)

Historical Context: Evangelista Torricelli

The concept of measuring pressure using a column of liquid is closely linked to Evangelista Torricelli, an Italian physicist and mathematician. In 1643, Torricelli invented the mercury barometer, demonstrating that atmospheric pressure could support a column of mercury. His experiments led to the understanding of vacuum and the quantification of atmospheric pressure. Britannica - Evangelista Torricelli has a good intro about him.

Real-World Applications and Examples

  • Aviation: Aircraft altimeters use inches of mercury to indicate altitude. Pilots set their altimeters to a local pressure reading (inHg) to ensure accurate altitude readings. Standard sea level pressure is 29.92 inHg.

  • Meteorology: Weather reports often include atmospheric pressure readings in inches of mercury. These readings are used to track weather patterns and predict changes in weather conditions. For example, a rising barometer (increasing inHg) often indicates improving weather, while a falling barometer suggests worsening weather.

  • Vacuum Systems: In various industrial and scientific applications, inches of mercury is used to measure vacuum levels. For example, vacuum pumps might be rated by the amount of vacuum they can create, expressed in inches of mercury. Higher vacuum levels (i.e., more negative readings) are crucial in processes like freeze-drying and semiconductor manufacturing. For example, common home vacuum cleaners operate in a range of 50 to 80 inHg.

  • Medical Equipment: Some medical devices, such as sphygmomanometers (blood pressure monitors), historically used mmHg (millimeters of mercury), a related unit. While digital devices are common now, the underlying principle remains tied to pressure measurement.

Interesting Facts

  • Standard Atmospheric Pressure: Standard atmospheric pressure at sea level is approximately 29.92 inches of mercury (inHg). This value is often used as a reference point for various measurements and calculations.

  • Altitude Dependence: Atmospheric pressure decreases with altitude. As you ascend, the weight of the air above you decreases, resulting in lower pressure readings in inches of mercury.

  • Temperature Effects: While "inches of mercury" typically refers to a standardized temperature, variations in temperature can slightly affect the density of mercury and, consequently, the pressure reading.

What is hectopascals?

Hectopascals (hPa) are a commonly used unit of pressure, particularly in meteorology. The following sections will detail what they are, how they relate to other units, and their real-world applications.

Definition of Hectopascal

A hectopascal (hPa) is a unit of pressure defined as 100 pascals (Pa). The pascal itself is the SI unit of pressure, defined as one newton per square meter (N/m2N/m^2). Therefore, 1 hPa is equivalent to 100 N/m2N/m^2.

1hPa=100Pa=100Nm21 \, hPa = 100 \, Pa = 100 \, \frac{N}{m^2}

Formation and Relationship to Other Units

The prefix "hecto" signifies a factor of 100. This makes the hectopascal a convenient unit for measuring atmospheric pressure, as it avoids the use of excessively large or small numbers. It's directly related to other units, most notably the millibar (mbar).

1hPa=1mbar1 \, hPa = 1 \, mbar

This equivalence is why you'll often see hPa and mbar used interchangeably in weather reports. The older unit of pressure, the atmosphere (atm), is approximately 1013.25 hPa at sea level under standard conditions.

Relevance to Meteorology

Hectopascals are the standard unit for reporting atmospheric pressure in meteorology. Weather maps and forecasts routinely use hPa to depict high and low-pressure systems. These pressure systems drive weather patterns. For example, low-pressure systems are often associated with clouds and precipitation, while high-pressure systems are typically associated with clear skies.

Real-World Examples

  • Standard Atmospheric Pressure: The standard atmospheric pressure at sea level is approximately 1013.25 hPa.
  • Hurricane Intensity: The strength of hurricanes is often described using the minimum central pressure in hPa. Lower pressures indicate a stronger storm. For example, Hurricane Wilma in 2005 had a record-low central pressure of 882 hPa.
  • Weather Maps: Isobars (lines connecting points of equal pressure) on weather maps are labeled in hPa. This allows meteorologists and the public to visualize pressure gradients, which are crucial for understanding wind patterns and weather systems.
  • Altitude Measurement: Pressure decreases with altitude. Aircraft altimeters use barometric pressure (measured in hPa or inches of mercury) to determine altitude.

Complete Inches of mercury conversion table

Enter # of Inches of mercury
Convert 1 inHg to other unitsResult
Inches of mercury to pascals (inHg to Pa)3386.3889532611
Inches of mercury to kilopascals (inHg to kPa)3.3863889532611
Inches of mercury to megapascals (inHg to MPa)0.003386388953261
Inches of mercury to hectopascals (inHg to hPa)33.863889532611
Inches of mercury to millibar (inHg to mbar)33.863889532611
Inches of mercury to bar (inHg to bar)0.03386388953261
Inches of mercury to torr (inHg to torr)25.400005965738
Inches of mercury to meters of water @ 4°C (inHg to mH2O)0.345315571909
Inches of mercury to millimeters of mercury (inHg to mmHg)25.400076155931
Inches of mercury to pounds per square inch (inHg to psi)0.491154
Inches of mercury to kilopound per square inch (inHg to ksi)0.000491154