# Torr to atm Converter

URL: https://speedycalculator.com/calculators/conversion/torr-to-atm/
Last updated: 2026-10-25

> Convert torr (Torr) to standard atmospheres (atm): 1 torr = 0.0013157895 atm, so multiply by 0.0013157895 or divide by 760. Both fields are editable, so you can also type in standard atmospheres and get torr back.

## Inputs

- Torr (Torr)

## Results

- Standard atmospheres

## Formula

```
1 Torr = 0.0013157895 atm
1 atm = 760 Torr
atm = Torr × 0.0013157895
```

## Explanation

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

- Type the number of torr into the **Torr** field. Decimals such as 380 are fine.
- Read the answer in **Standard atmospheres** – it updates as you type, with no button to press.
- To convert the other way, type into **Standard atmospheres** and the torr are recalculated.
- 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

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

### Torr to atm conversion table

TorrStandard atmospheresStandard atmospheresTorr1 Torr0.0013157895 atm1 atm760 Torr10 Torr0.013157895 atm2 atm1,520 Torr100 Torr0.13157895 atm5 atm3,800 Torr200 Torr0.26315789 atm10 atm7,600 Torr380 Torr0.5 atm20 atm15,200 Torr500 Torr0.65789474 atm50 atm38,000 Torr760 Torr1 atm100 atm76,000 Torr1,000 Torr1.3157895 atm1,000 atm760,000 Torr

### 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.

## Worked example

Inputs — Torr: 760 Torr.

Results — **Standard atmospheres = 1 atm**.

## FAQ

**How many torr in an atmosphere?**
760.

**Is 1 torr the same as 1 mmHg?**
Practically yes; they differ by less than 0.000015%.

**How many standard atmospheres are in one torr?**
1 Torr = 0.0013157895 atm.

**How many torr are in one standard atmosphere?**
1 atm = 760 Torr.

**How do I convert torr to standard atmospheres?**
Multiply the number of torr by 0.0013157895. For example, 760 Torr × 0.0013157895 = 1 atm.

**How do I convert standard atmospheres back to torr?**
Divide by 0.0013157895 (or multiply by 760), or simply type the value into the standard atmospheres field above.

**What is 10 Torr in standard atmospheres?**
10 Torr = 0.013157895 atm.

**What is 100 Torr in standard atmospheres?**
100 Torr = 0.13157895 atm.

**Is this conversion exact?**
Yes. The factor comes from the official definitions of both units (NIST and the SI), so the only difference you may see is rounding in the last displayed digit.

**Can I convert to other units on this page?**
This page converts only between torr and standard atmospheres. To pick any pressure unit, use the general pressure converter linked under Related calculators.

**What formula does the Torr to atm Converter use?**
1 Torr = 0.0013157895 atm.


## Sources

- [NIST Special Publication 811 – Guide for the Use of the International System of Units](https://www.nist.gov/pml/special-publication-811)
- [NIST Handbook 44 Appendix C – General tables of units of measurement](https://www.nist.gov/pml/owm/nist-handbook-44-current-edition)