# Torr to Atm Conversion

By Wojciech Sas, PhD candidate
Last updated: Jan 11, 2021

This is the `Torr` to `atm` conversion calculator - a great tool that helps you convert torrs to atms (standard atmospheres). It also works the other way around, enabling `atm` to `Torr` conversion.

You'll find the torr's unit definition and the relationships between `Torr`, `atm`, `mmHg`, and many other pressure units in the article. You'll see how easy it is to move from `mmHg` to `atm` and vice versa in a millisecond.

What is the atmospheric pressure in torrs? How many torrs are in `1 atm`? How many `mmHg` are in `1 atm`? - If you've ever asked one of these questions, this is the right place to get the answer!

## Torr unit - Is Torr equivalent to mmHg?

Let's start from the basic definition - a torr is the unit of pressure. One `Torr` is precisely `1/760` of a standard atmosphere, `atm`. The name comes from Evangelista Torricelli, who was an Italian physicist and mathematician and was a pioneer of pressure measurements.

Historically, the first barometers consisted of mercury (Hg) inside a vertical glass, so the natural pressure unit was `mmHg` (or `mm Hg`), millimeter of mercury.

 💡 `One mmHg` is the pressure of a `1 mm` high mercury column (assuming the temperature is `32°F/0°C` and the gravitational acceleration equals `9.80665m/s²`).

`Torr` and `mmHg` are almost the same units. So how to convert `Torr` to `mmHg`?

• `1 Torr = 0.9999998575337… mmHg`.

For completeness, here is how to move from `mmHg` to `Torr` as well:

• `1 mmHg = 1.0000001424663203… Torr`.

If we accept the accuracy of up to 6 significant figures, we can assume there is no difference between `1 Torr` and `1 mmHg`.

## How many torrs are in 1 atm?

According to the previous section's definition, there are exactly `760` torrs in one standard atmosphere (as one `Torr` is precisely `1/760` of one `atm`).

We can always convert this fraction to decimal, so the `atm` to `Torr` conversion factor equals `0.00131578947…`. As you can see, using the fraction form is more convenient and prevents losing precision during computations.

The good thing is that you can also use our Torr to atm conversion as an atm to Torr conversion. Moreover, you can even change the units yourself to make it an `mmHg` to `atm` or `atm` to `mmHg` converter.

So what about `mmHg` to `atm` conversion? What are the numbers here?

• `1 mmHg = 0.00131578966… atm`; or
• `1 mmHg = 1/759.99989157… atm`.

And if you want to know how many `mmHg` are in `1 atm`, then the answer is:

• `1 atm = 759.99989157… mmHg`.

## How to convert Torr to atm using Torr to atm conversion?

Our tool is as simple as it could be! Assuming you want to convert `800 Torr` to `atm`, these are the steps you should follow:

1. Type `800` in the field with `Torr` unit;

2. Multiply `800` by the convertion factor, `800 Torr * 1/760 = 1.0526 atm`; and

3. That's all! The answer is `1.0526 atm`.

And what if you want to convert the pressure of `2.5` atmospheric pressure to torrs? Analogically:

1. Input `2.5 atm` into the second field;

2. Multiply `2.5` by `760`; and

3. Read that your value is equivalent to `1900 Torr`.

Whenever you want to use technical atmospheres instead of standard ones or `mmHg` instead of `Torr`, simply change the units with just one click!

## Torr to other pressure units list

`Torr`, `atm`, or `mmHg` are not the only pressure units we are commonly using. There are others, both metric and imperial units, such as pascals (`Pa`) or pounds per square inch (`psi`), to mention a few.

If you deal with a task of a Torr to other unit conversions, here are some of the examples (rounded to six decimal places):

• `1 Torr ≈ 133.322368 Pa`;
• `1 Torr ≈ 1.333223 hPa`;
• `1 Torr ≈ 0.133322 kPa`;
• `1 Torr ≈ 0.019337 psi`;
• `1 Torr ≈ 2.784437 lbs/ft²`;
• `1 Torr ≈ 0.001333 bar`;
• `1 Torr ≈ 0.001359 at`;
• `1 Torr ≈ 0.039370 in Hg`;
• `1 Torr ≈ 1.359510 cm H₂O`.
Wojciech Sas, PhD candidate
Torr to atm conversion
Torr
atm
Conversion to other units
Metric
Pa
Imperial
psi
Others
kN/m²
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