Torr to atm Converter

The torr is defined as exactly 1/760 of a standard atmosphere, after Evangelista Torricelli. Vacuum gauges and gas-law problems often use it.

How to use the Torr to atm Converter

1. Type the number of torr into the Torr field. Decimals such as 380 are fine.
2. Read the answer in Standard atmospheres – it updates as you type, with no button to press.
3. To convert the other way, type into Standard atmospheres and the torr are recalculated.
4. Press Copy results to copy both values with the page title, or Copy link to share this exact conversion.

This page converts only Torr ⇄ atm. Need a different unit? Use the general pressure converter, where you can choose any “from” and “to” unit.

How it works

Both units measure pressure, so they are always in the same ratio: one torr equals 0.0013157895 standard atmospheres. The calculator multiplies the number of torr you type by 0.0013157895 to give standard atmospheres, and when you type into the standard atmospheres field it divides by the same factor to give torr. Because the ratio never changes, doubling the torr always doubles the standard atmospheres. Results are calculated at full precision and rounded only for display (up to eight decimal places, with very large or small values shown in scientific notation).

How to convert torr to standard atmospheres

1. Write down the value in torr, for example 760 Torr.
2. Multiply by the conversion factor 0.0013157895 (because 1 torr = 0.0013157895 atm).
3. 760 × 0.0013157895 = 1 atm.
4. To go back from standard atmospheres to torr, divide by 0.0013157895 – or multiply by 760.

Torr to atm conversion table

What is a torr?

The torr is exactly 1/760 of a standard atmosphere, named after Evangelista Torricelli, inventor of the barometer. Vacuum systems are rated in torr.

What is a standard atmosphere?

The standard atmosphere is exactly 101,325 Pa, the average air pressure at sea level. Chemistry problems and diving depth calculations often use atm.

Quick mental conversion

For a fast estimate, multiply torr by about 0.0013 to get standard atmospheres; the error is about 1.2%. Use the calculator above when you need the exact figure.

Common mistakes to avoid

Mixing gauge pressure (psig, barg) with absolute pressure (psia, bara), treating bar and atm as identical, and confusing kgf/cm² with bar.