Convert barometric pressure between atmospheres, bar, PSI, kPa, mmHg, inHg, hectopascals, and millibars. Includes reference pressure table and preset values.
Barometric pressure—the weight of the atmosphere pressing down at a given location—is expressed in a bewildering variety of units depending on the field. Meteorologists in the United States report inches of mercury (inHg), while European weather services use hectopascals (hPa) or millibars (mbar). Pilots read altimeter settings in inHg or hPa, scientists work in atmospheres (atm) or kilopascals (kPa), and tire mechanics talk in PSI.
This converter handles eight of the most widely used pressure units simultaneously. Enter a value in any unit and instantly see the equivalent in all seven other units—no need to chain multiple conversions. Whether you are checking weather forecasts from different countries, adjusting lab equipment, calibrating pressure gauges, or converting between tire-pressure standards, this single tool replaces a dozen lookup tables.
Preset buttons load common reference values such as standard atmospheric pressure (1 atm = 14.696 PSI = 101.325 kPa = 760 mmHg) so you can instantly verify your intuition or use them as starting points for related conversions.
Pressure conversions involve non-obvious factors that are easy to misremember. One atmosphere equals 14.696 PSI, 101.325 kPa, 760 mmHg, 29.9213 inHg, and 1013.25 hPa—memorizing all of those is impractical. This calculator removes the guesswork and eliminates rounding errors by computing every conversion to six significant figures. Keep these notes focused on your operational context.
All conversions route through atmospheres (atm): Value in atm = Input × (1 / factor_from_atm) Result = atm × factor_to_target Factors: 1 atm = 1.01325 bar = 14.696 PSI = 101.325 kPa = 760 mmHg = 29.9213 inHg = 1013.25 hPa = 1013.25 mbar
Result: 14.696 PSI
Standard atmospheric pressure (1 atm) equals 14.696 pounds per square inch. This is the baseline pressure at sea level under standard conditions.
Pressure is force per unit area. The SI unit is the pascal (Pa), but because one pascal is extremely small, practical measurements use kilopascals (kPa), hectopascals (hPa), bar, or traditional units like atmospheres and mmHg. Each unit arose in a different context—atmospheres from gas-law experiments, mmHg from mercury barometers, PSI from mechanical engineering—so cross-field conversions are a daily necessity.
In meteorology, even small pressure differences (1–2 hPa) can indicate approaching weather fronts. In tire maintenance, a difference of 2–3 PSI can affect fuel efficiency and handling. In laboratory settings, vacuum pressures must be specified precisely in Torr or mbar. Always use a reliable converter rather than rounding approximations.
Standard atmospheric pressure is defined as 1 atm, which equals 101.325 kPa, 14.696 PSI, 760 mmHg, 29.9213 inHg, and 1013.25 hPa. It represents the average air pressure at sea level under standard conditions.
Yes. Hectopascals (hPa) and millibars (mbar) are numerically identical. 1 hPa = 1 mbar = 100 Pa. The World Meteorological Organization prefers hPa, but many weather services still use mbar.
Historical convention varies by country. The US uses inches of mercury (inHg), most of Europe and international aviation use hectopascals (hPa), and some scientific contexts use kilopascals or atmospheres.
Pressure decreases roughly 12 hPa (0.36 inHg) per 100 meters of altitude gain in the lower atmosphere. At the summit of Mount Everest (8,849 m), pressure is about one-third of sea-level pressure.
Torr is a pressure unit very nearly equal to 1 mmHg. Precisely, 1 Torr = 1/760 atm = 133.322 Pa. It is commonly used in vacuum science and blood-pressure measurement.
Divide the PSI value by 14.5038. For example, 30 PSI ÷ 14.5038 ≈ 2.069 bar. Alternatively, multiply PSI by 0.0689476.