Convert atmospheres (atm) to and from Pascals, kPa, bar, psi, mmHg, Torr, and inHg. Bidirectional conversion with preset values, reference table, and quick formulas.
The atmosphere (atm) is one of the most widely recognized pressure units, defined as the average pressure exerted by the Earth's atmosphere at sea level. One standard atmosphere equals exactly 101,325 Pascals, 14.696 pounds per square inch, 1.01325 bar, and 760 millimeters of mercury. This unit is fundamental in chemistry (standard temperature and pressure), physics (gas laws), meteorology, and diving.
This ATM pressure converter allows you to instantly convert between atmospheres and seven other common pressure units: Pascals, kilopascals, bar, psi, mmHg, Torr, and inches of mercury. The tool is fully bidirectional — select any unit as your input and see all other units update simultaneously.
Whether you are a student working through Boyle's law problems, a diver calculating pressure at depth, or an engineer comparing specifications in different unit systems, this converter eliminates the need to memorize conversion factors. Just enter your value and get instant, accurate results for lab, field, and documentation workflows.
Pressure is expressed in many different units depending on the field and country. Atmospheres are common in chemistry and diving, Pascals in physics and engineering, psi in American industry, and mmHg in medicine. Converting between these units manually requires remembering precise conversion factors. This tool handles all conversions instantly and includes reference pressures for context.
atm to Pascals: Pa = atm × 101,325 atm to kPa: kPa = atm × 101.325 atm to bar: bar = atm × 1.01325 atm to psi: psi = atm × 14.696 atm to mmHg: mmHg = atm × 760 atm to Torr: Torr = atm × 760 atm to inHg: inHg = atm × 29.9212
Result: 29.392 psi
2 atm is the approximate pressure experienced 10 meters underwater. Using the formula: psi = 2 × 14.696 = 29.392 psi. This is also equal to 202,650 Pa, 202.65 kPa, and 2.0265 bar.
Atmospheric pressure is the force per unit area exerted by the weight of the atmosphere above a surface. At sea level, this force equals approximately 101,325 Newtons per square meter. The concept was first demonstrated by Torricelli in 1643 using a mercury barometer, which is why mmHg remains a common pressure unit.
Different fields prefer different pressure units. Chemistry uses atm for standard conditions. Engineering uses Pa or kPa (SI system) or psi (US customary). Medicine uses mmHg for blood pressure and respiratory measurements. Meteorology uses millibars (mbar) or hectopascals (hPa). Diving uses atm or bar for depth calculations.
The ideal gas law PV = nRT requires pressure in Pascals when using SI units. Boyle's law (P₁V₁ = P₂V₂) and Dalton's law of partial pressures are fundamental to chemistry and physics. Understanding pressure unit conversion is essential for correctly applying these laws.
1 standard atmosphere equals 14.696 pounds per square inch (psi). This conversion is commonly used when comparing metric and imperial pressure measurements in engineering and automotive applications.
1 atm equals exactly 101,325 Pascals (Pa) or 101.325 kilopascals (kPa). The Pascal is the SI unit of pressure, defined as one newton per square meter.
The two units are very close: 1 atm = 1.01325 bar. The bar is a metric unit equal to 100,000 Pa, while the atmosphere is defined as 101,325 Pa. The bar is commonly used in European weather reports and industrial applications.
Evangelista Torricelli invented the mercury barometer in 1643. At standard atmospheric pressure, the column of mercury in a barometer rises to exactly 760 mm. This is why 1 atm = 760 mmHg = 760 Torr.
Atmospheric pressure decreases roughly 12% per 1,000 meters of altitude gain. At sea level it is 1 atm, at Denver (1,600 m) about 0.83 atm, and at the summit of Everest (8,849 m) only 0.33 atm.
Absolute pressure is measured from perfect vacuum (0 atm). Gauge pressure is measured relative to atmospheric pressure, so 0 gauge = 1 atm absolute. A tire at 32 psig (gauge) has an absolute pressure of about 32 + 14.7 = 46.7 psia.