General
ATM Conversion Calculator
Convert between atmospheric pressure (atm) and other common pressure units
Enter a value and select units to see the conversion result
The ATM Conversion Calculator is a specialized tool designed to convert between different pressure units, with atmospheric pressure (atm) as a central reference point. It uses precise conversion factors based on established scientific standards to ensure accurate conversions between common pressure units including atmospheres (atm), pounds per square inch (PSI), pascals (Pa), bars, torr, and millimeters of mercury (mmHg).
Key Conversion Factors
1 atm = 14.6959 PSI
1 atm = 101,325 Pascal
1 atm = 1.01325 Bar
1 atm = 760 Torr/mmHg
The calculator performs conversions by first converting the input value to atmospheres (atm) as an intermediate step, then converting from atmospheres to the desired output unit. This two-step process ensures consistent and accurate results across all unit combinations.
Different pressure units are used across various fields and industries. Understanding these units and their relationships is crucial for accurate measurements and calculations:
Common Pressure Units
- Atmosphere (atm): The average pressure exerted by Earth's atmosphere at sea level.
- PSI (Pounds per Square Inch): Commonly used in engineering and tire pressure measurements.
- Pascal (Pa): The SI unit of pressure, used in scientific calculations.
- Bar: Approximately equal to atmospheric pressure, common in meteorology.
- Torr & mmHg: Used in vacuum measurements and medical blood pressure readings.
1. Why are there so many different pressure units?
Different pressure units evolved from various practical applications and historical contexts. For example, mmHg came from mercury barometers, PSI from engineering applications, and Pascal from scientific standardization efforts. Each unit serves specific purposes in different fields.
2. Which pressure unit should I use?
The choice of pressure unit depends on your application. Use PSI for tire pressure, mmHg for medical readings, Pascal for scientific work, atmospheres for general reference, and bars for weather forecasting. Industry standards often dictate which unit to use.
3. Why is atmospheric pressure used as a reference?
Atmospheric pressure (1 atm) serves as a natural reference point because it represents the average pressure at sea level on Earth. This makes it a convenient baseline for comparing and understanding other pressure measurements.
4. Are Torr and mmHg the same?
Yes, Torr and millimeters of mercury (mmHg) are effectively the same unit. One Torr equals one millimeter of mercury. The term "Torr" was named after Evangelista Torricelli, who invented the mercury barometer.
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 International System of Units (SI). The fundamental relationship between units is based on the standard atmospheric pressure defined as 101,325 Pascal or 1 atmosphere. These conversions are derived from physical measurements and international standards maintained by metrology institutes worldwide.