Torr to atm Calculator — Pressure Unit Converter
Convert any pressure between Torr (mmHg) and standard atmospheres instantly, plus get the equivalent in Pa, kPa, bar and psi.
Input unit
1 atm = 760 Torr exactly
- 1
Pascals
760 × 133.322 = 101,3251 Torr = 101,325 ÷ 760 Pa ≈ 133.322 Pa. - 2
Atmospheres
101,325 ÷ 101,325 = 1
How does this calculator work?
1 atm = 760 Torr (exact). To convert Torr to atm divide by 760; to convert atm to Torr multiply by 760. The calculator also shows the equivalent in Pa, kPa, bar and psi, with a number-line view of the pressure on an atmospheric scale.
Formula
How this is calculated
The Torr was originally defined to equal one millimetre of mercury (mmHg) under standard gravity — the pressure that supports a 1 mm column of mercury at 0 °C and g = 9.80665 m/s². Since 1954 the Torr has been defined precisely as 1/760 of a standard atmosphere, where 1 atm = 101 325 Pa exactly. This means 1 Torr = 101 325/760 Pa ≈ 133.322 Pa. In practice, 1 Torr and 1 mmHg differ by less than 0.00016%, so they are interchangeable in almost all laboratory contexts.
The standard atmosphere (atm) is an exact defined constant equal to 101 325 Pa. It represents the average air pressure at sea level and is the reference point for many chemical and physical tables. A pressure of 760 Torr is therefore exactly 1 atm.
This converter also outputs kilopascals (divide Pa by 1000), bar (divide Pa by 100 000), and psi (divide Pa by 6894.757). All conversions are mathematically exact or rounded only at display time.
Frequently asked questions
Almost. Before 1954, 1 Torr was defined as the pressure of exactly 1 mm of mercury. Today both are in common use and differ by only 0.00016%. For practical purposes in science and medicine they are interchangeable, but the Torr is now an exact sub-unit of the atm (1 atm = 760 Torr exactly).
1 atm = 101 325 Pa exactly — an international constant that approximates sea-level air pressure. It is used as a reference in gas laws, thermodynamic tables, and as a unit for moderate pressures in chemistry.
Torr is common in vacuum technology (rough to high vacuum), blood pressure measurement (traditionally in mmHg), gas chromatography, and astronomy. Pa and bar dominate in SI-based engineering. Meteorologists prefer hPa (= mbar).
Also known as
TG we-Calculate Editorial Team. (2026). Torr to atm Calculator — Pressure Unit Converter [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/torr-to-atm-calculator
TG we-Calculate Editorial Team. "Torr to atm Calculator — Pressure Unit Converter." TG we-Calculate. 2026. https://we-calculate.com/calculator/torr-to-atm-calculator.
TG we-Calculate Editorial Team, "Torr to atm Calculator — Pressure Unit Converter," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/torr-to-atm-calculator
@misc{wecalculate_torr_to_atm_calculator, title = {Torr to atm Calculator — Pressure Unit Converter}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/torr-to-atm-calculator}}, year = {2026}, note = {TG we-Calculate} }
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