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Torr to Atmospheres Converter
↔ Convert atm to torr instead

Common Conversions

torr atm
0.001 0.00000132
0.01 0.0000132
0.1 0.000132
1 0.001316
10 0.01316
50 0.06579
100 0.1316
200 0.2632
380 0.5
500 0.6579
760 1
1520 2

Why this conversion matters in chemistry

Vacuum work almost always lives in torr — rotary evaporators at 10 to 100 torr, Schlenk lines at 10⁻² to 10⁻³ torr, high-vacuum systems several decades lower. But any calculation that plugs a pressure into the ideal gas law with R = 0.08206 L·atm/(mol·K), or into a Clausius–Clapeyron fit for sublimation enthalpy, needs atm. Dividing by 760 is the bridge. 380 torr is half an atmosphere; 23.8 torr is the vapor pressure of water at 25°C, or 0.0313 atm. The conversion is exact — no precision trade-off — but forgetting it silently drops a pressure reading by a factor of 760.

Formula

atm = torr / 760

Worked Examples

760 torr = 1 atm

The defining equivalence. One atmosphere is 760 torr by historical convention.

23.8 torr = 0.0313 atm

Water's vapor pressure at 25°C. The correction you subtract when collecting a gas over water to get the dry-gas partial pressure.

1 torr = 0.001316 atm

A low to moderate vacuum. Achievable on a rotary pump in reasonable condition — below where a water aspirator can reach.

380 torr = 0.5 atm

Half an atmosphere — roughly the ambient air pressure at around 5500 m elevation.

Frequently Asked Questions

How do I convert torr to atm?
Divide by 760. So 380 torr is 0.5 atm, and 100 torr is about 0.132 atm. The factor is exact by definition — the torr was pinned to 1/760 of a standard atmosphere, so no precision is lost in either direction.
What's the difference between torr and mmHg?
Almost nothing in practice. The torr is defined as exactly 1/760 atm by convention, while mmHg is tied to a specific mercury density and gravity. The numerical difference is less than 2 parts in 10⁷ — you'll never notice. Treat them as interchangeable.
Why does vacuum work stay in torr?
Because the numbers read cleanly at vacuum scales. A rotary evaporator at 10–50 torr, a Schlenk line at 0.01–0.1 torr, high-vacuum systems around 10⁻⁶ torr. Writing those same pressures in atm pushes you into 10⁻⁵ or 10⁻⁹ territory, which is awkward to read and compare.
When should I convert torr to atm?
Whenever the downstream calculation expects atm. The ideal gas law with R = 0.08206 L·atm/(mol·K) wants atm; Dalton's-law partial-pressure calculations against other atm-based values want atm. Mixed-unit gas-law calculations are where unit errors hide most effectively.