General
Barometric Pressure Conversion Calculator
Convert barometric pressure measurements between different units commonly used in meteorology and atmospheric science.
Enter a value and select units to see the conversion result
Related to Barometric Pressure Conversion Calculator
The Barometric Pressure Conversion Calculator is designed to convert barometric pressure readings between different units commonly used in meteorology, aviation, and scientific applications. The calculator uses precise conversion factors based on established standards to ensure accurate conversions between inches of mercury (inHg), millimeters of mercury (mmHg), hectopascals (hPa), millibars (mbar), kilopascals (kPa), atmospheres (atm), and pounds per square inch (psi).
Key Conversion Factors
1 inHg = 25.4 mmHg
1 inHg = 33.8639 hPa/mbar
1 inHg = 3.38639 kPa
1 inHg = 0.03342 atm
1 inHg = 0.49115 psi
The calculator performs conversions by first converting the input value to inches of mercury (inHg) as an intermediate step, then converting from inHg to the desired output unit. This two-step process ensures consistent and accurate results across all unit combinations. The conversion factors are based on standard physical constants and relationships established by international meteorological organizations.
Different barometric pressure units are used across various fields and regions. Understanding these units and their typical applications helps in selecting the most appropriate unit for your needs:
Common Units and Their Uses
- Inches of Mercury (inHg): Standard unit for weather reporting in the United States
- Millimeters of Mercury (mmHg): Used in medical applications and some international weather reports
- Hectopascals (hPa) & Millibars (mbar): Standard units in meteorology and international weather forecasting
- Kilopascals (kPa): SI unit commonly used in scientific and engineering applications
- Atmospheres (atm): Used as a reference unit, representing average sea-level pressure
- Pounds per Square Inch (psi): Common in engineering and industrial applications
Standard sea-level pressure is approximately 29.92 inHg, 760 mmHg, 1013.25 hPa/mbar, 101.325 kPa, 1 atm, or 14.696 psi. Weather forecasters typically report changes in pressure relative to these standard values to indicate atmospheric conditions and potential weather changes.
1. Why are there so many different pressure units?
Different pressure units evolved from various historical and practical needs. For example, inches and millimeters of mercury came from early barometers that used mercury columns, while pascals were introduced as part of the metric system. Each unit continues to serve specific purposes in different fields and regions.
2. Are millibars (mbar) and hectopascals (hPa) the same?
Yes, millibars and hectopascals are exactly the same unit with different names. 1 mbar = 1 hPa. The term "millibar" is older and still commonly used in weather forecasting, while hectopascal is the modern SI unit name for the same pressure measurement.
3. Which pressure unit should I use?
The choice depends on your location and application. In the US, use inHg for weather reports. For international weather, use hPa/mbar. For scientific work, use kPa or atm. For medical applications, mmHg is standard. For engineering applications, psi is commonly used.
4. How accurate are these conversions?
The conversions are highly accurate, using precise conversion factors established by international standards. The calculator maintains 6 decimal places of precision to ensure accuracy for both small and large pressure values. However, when reading barometric pressure for weather purposes, 2-3 decimal places are typically sufficient.
5. What is the scientific source for this calculator?
This calculator uses conversion factors established by the National Institute of Standards and Technology (NIST) and the World Meteorological Organization (WMO). The relationships between units are based on the international standard atmosphere defined by the International Civil Aviation Organization (ICAO) and the International Standard Atmosphere (ISA) model. The conversion factors are derived from fundamental physical constants and relationships maintained by these authoritative organizations to ensure worldwide consistency in meteorological measurements and reporting.