ATM to Pascals Conversion Calculator
Enter a pressure in standard atmospheres (atm) and instantly get the equivalent in pascals (Pa), kilopascals (kPa), megapascals (MPa), bar, PSI, and mmHg — all from the single exact conversion factor defined by the BIPM.
atm
1 atm = 101 325 Pa (BIPM exact definition)
- 1
Conversion factor
1 atm = 101,325 Pa = 101,325Exact by BIPM definition (1954) — no rounding error. - 2
Multiply to get pascals
1 × 101,325 = 101,325
How does this calculator work?
Multiply atm by 101 325 to get pascals — this is exact by BIPM definition. 1 atm = 101 325 Pa = 101.325 kPa = 1.01325 bar = 14.696 PSI = 760 mmHg. Enter any atm value to see all common pressure units at once.
Formula
How this is calculated
The standard atmosphere (atm) is a unit of pressure equal to exactly 101 325 pascals by definition from the International Bureau of Weights and Measures (BIPM, 1954). It was historically based on the average atmospheric pressure at sea level. Because the conversion factor is exact, there is no rounding error in the Pa result — only in derived units like PSI that use non-integer factors.
All secondary units are derived from pascals using exact or high-precision factors: 1 bar = 100 000 Pa, 1 kPa = 1 000 Pa, 1 psi = 6 894.757 293 Pa, and 1 mmHg (Torr) = 133.322 387 Pa. These secondary conversions introduce negligible floating-point rounding at the displayed decimal places.
The standard atmosphere differs from a technical atmosphere (at, 1 kgf/cm² ≈ 98 066.5 Pa) and from actual local atmospheric pressure, which varies with altitude and weather. Use this calculator for unit conversion; for actual atmospheric conditions at altitude, use a barometric formula tool.
Frequently asked questions
1 standard atmosphere is exactly 101 325 pascals (Pa) by the 1954 BIPM definition. This is not an approximation — it is exact.
1 atm = 1.01325 bar. The bar (100 000 Pa) is often used in meteorology and engineering. It is close to 1 atm but slightly less. Many weather reports use hectopascals (hPa = mbar), where 1 atm ≈ 1013.25 hPa.
Multiply atm by 14.696. For example, 2 atm = 29.39 PSI. More precisely: 1 atm = 14.6959 PSI (using the exact factors 101 325 Pa / 6 894.757 Pa per PSI).
Also known as
TG we-Calculate Editorial Team. (2026). ATM to Pascals Conversion Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/atm-to-pascals-conversion-calculator
TG we-Calculate Editorial Team. "ATM to Pascals Conversion Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/atm-to-pascals-conversion-calculator.
TG we-Calculate Editorial Team, "ATM to Pascals Conversion Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/atm-to-pascals-conversion-calculator
@misc{wecalculate_atm_to_pascals_conversion_calculator, title = {ATM to Pascals Conversion Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/atm-to-pascals-conversion-calculator}}, year = {2026}, note = {TG we-Calculate} }
Did this calculator help you?