Convert between kilopascals and atmospheres with bidirectional conversion, Pa/bar/psi equivalents, and reference table.
Kilopascals and atmospheres are both common pressure units, but they signal different contexts. kPa is the practical SI-style unit used in engineering, weather, and equipment specs, while atm is the classic chemistry and gas-law reference pressure. They are close enough to be easy to compare, yet different enough that the conversion factor matters when you are solving a gas law, reading a weather map, or checking an equipment specification.
This converter handles both directions and also shows Pa, bar, psi, and mmHg. That makes it useful when a reading in kPa has to be compared with a chemistry value in atm, or when an atmosphere-based reference needs to be translated into a more engineering-friendly number. It also helps when a lab report, a diving table, or a reference chart uses atm but the rest of your workflow is written in metric pressure units.
Use it when you need to move between metric pressure reporting and atmosphere-based scientific reference points without memorizing the 101.325 factor. The reference table gives you quick checks for common pressures instead of making you recalculate the same ratio over and over.
kPa and atm describe the same pressure in two communities that often talk past each other. This page keeps both views visible and makes it easier to compare engineering values with chemistry, weather, and diving references, which is useful whenever a calculation crosses from one convention into the other. It is also a practical guardrail against rounding a result too early and losing the precision you need for a gas-law or reference-pressure check.
kPa to atm: atm = kPa ÷ 101.325 atm to kPa: kPa = atm × 101.325 kPa to psi: psi = kPa × 0.145038 kPa to bar: bar = kPa ÷ 100
Result: 1.974 atm
200 kPa ÷ 101.325 = 1.974 atm. This is roughly twice atmospheric pressure, similar to the pressure at 10 meters under water.
The mole concept in chemistry traditionally uses STP at 0°C and 1 atm (101.325 kPa), giving a molar volume of 22.414 L/mol for ideal gases. The newer IUPAC standard uses 0°C and 100 kPa (1 bar), giving 22.711 L/mol.
Use atm when solving gas law problems in general chemistry courses (unless instructed otherwise). Use kPa in engineering calculations, when working with SI units, or when using R = 8.314. International standards increasingly prefer kPa or bar over atm.
Medical: mmHg (blood pressure). Chemistry: atm or bar. Engineering: kPa, MPa, or psi. Meteorology: hPa, kPa, or mbar. Diving: atm or bar. This converter helps bridge all these unit systems.
1 atm = 101.325 kPa exactly. This is the defined standard atmospheric pressure, so the conversion does not vary from one source to another.
Divide the kPa value by 101.325. For example, 150 kPa ÷ 101.325 = 1.481 atm, which is the same relationship this page uses in the opposite direction as well.
No, but they are close. 100 kPa = 1 bar = 0.9869 atm, while 1 atm = 101.325 kPa, so the difference is about 1.3%.
Use R = 8.314 L·kPa/(mol·K) when pressure is in kPa and volume in liters. With atm, use R = 0.08206 L·atm/(mol·K), so the gas-law units stay consistent.
Canada and some other countries use kPa for weather because it is an SI unit. Normal weather pressure ranges from about 97 to 104 kPa, which is why the unit works well for daily forecasts and synoptic maps.
1 kPa = 10 hPa (hectopascals). Meteorologists often use hPa, which is the same numerical scale as millibars, so standard pressure becomes 1013.25 hPa = 101.325 kPa.