Convert Pressure from torr to bar

Torr to Bar Conversion Formula

To convert a pressure from torr to bar, multiply by 0.00133322.

• bar = torr × 0.00133322

One torr is exactly 101,325/760 Pa ≈ 133.322 Pa, and a bar is exactly 100,000 Pa; the ratio is 0.0013332. The two round-number anchors are 750 torr ≈ 1 bar (within 0.01%) and 760 torr = 1.01325 bar exactly, the standard atmosphere.

Step-by-Step Example

A freeze-dryer runs at 200 torr during its primary drying stage, and a European qualification document wants the figure in bar:

1. Take the pressure: 200 torr
2. Multiply by 0.00133322: 200 × 0.00133322 = 0.2667 bar

Quick Reference Table

Reading Vacuum Depths in Bar

Torr numbers get small fast — rough vacuum spans 760 down to about 1 torr, high vacuum begins around 10⁻³ torr, and ultra-high vacuum lives below 10⁻⁹ torr — so converting to bar mostly produces long strings of leading zeros (10⁻³ torr is 1.3 × 10⁻⁶ bar). That is why the bar's milli sibling owns European vacuum paperwork instead: 1 torr = 1.333 mbar keeps the digits manageable, and a datasheet's "ultimate pressure 2 × 10⁻³ mbar" meets an American gauge reading of 1.5 × 10⁻³ torr on almost equal terms. The conversion to full bar earns its place at the top of the range, where vacuum work meets ordinary engineering: a 200-torr process step is 0.27 bar absolute, a leak-test differential of 500 torr is 0.67 bar, numbers a pressure-vessel or piping engineer can drop straight into their usual formulas.

Torr figures are absolute by convention — zero is a perfect vacuum. Keep them absolute through the conversion: 0.2667 bar absolute in the example above, which a gauge referenced to the room would show as roughly −0.75 bar. The negative gauge reading and the positive absolute figure describe the same chamber.

How many torr are in one bar? One bar (bar) contains 750.0616827041697508 torr (torr) — the inverse of the factor above. Multiplying by 0.0013332236842105263158 takes you from torr to bar; multiplying by 750.0616827041697508 brings you back.

Put in words: one torr equals 0.0013332236842105263158 bar, so the torr is the smaller unit of this pair. Converting between them never changes the amount of pressure being measured — only the size of the unit you count it in.

What Is a Torr?

A torr (Torr) is a unit of pressure.

It is primarily used to measure a vacuum, or pressures much lower than the air pressure we experience every day.

While the modern standard (SI) unit for pressure is the pascal (Pa), the torr is still widely used in many scientific and engineering fields.

For conversion, one torr is equal to about 133.32 pascals.

A much simpler way to think about it is in relation to our atmosphere: one standard atmosphere (atm) is defined as exactly 760 Torr.

Where Did the Torr Come From?

The unit is named in honor of Evangelista Torricelli, the 17th-century Italian physicist who invented the mercury barometer.

Because of this, one torr was initially defined as being equal to one millimeter of mercury (mmHg).

This means 1 Torr is the pressure exerted by a column of mercury that is one millimeter high.

Torr vs. Atmosphere (atm)

As mentioned, the torr's most convenient relationship is with the standard atmosphere (atm).

One standard atmosphere—the average air pressure at sea level—is set at exactly 760 Torr.

This straightforward, whole-number conversion makes the torr a popular choice for anyone working with fractions of atmospheric pressure.

Where Is the Torr Used Today?

The torr is the primary unit of measurement for high-vacuum and ultra-high-vacuum technology.

Because it is such a small unit (it takes 760 of them to equal one atmosphere), it is ideal for quantifying pressures far below normal air pressure.

You will find the torr used in many advanced scientific and industrial fields, including:

• Semiconductor manufacturing
• Thin-film deposition (like adding anti-reflective coatings to glasses)
• Mass spectrometry
• Particle accelerators
• Vacuum furnaces

What is a bar (bar)?

The bar is a metric unit of pressure.

It is defined as exactly 100 kilopascals (kPa), or 100,000 Pascals (Pa).

Although it is not an official part of the International System of Units (SI), it is widely accepted for use with the SI. The bar is a popular unit for measuring pressure because it is very close to the average atmospheric pressure on Earth at sea level.

Origin of the Bar

The term "bar" comes from the Greek word βάρος (baros), which means "weight."

The unit was introduced by British meteorologist William Napier Shaw in 1909. It is still widely used in meteorology, oceanography, and engineering.

Bar vs. Standard Atmosphere (atm)

A common point of confusion is the difference between a bar and a standard atmosphere (atm).

While they are very close in value, they are not the same:

• 1 bar = 100,000 Pascals (Pa)
• 1 atmosphere (atm) = 101,325 Pascals (Pa)

This means 1 bar is approximately equal to 0.987 atm. Because it's so close to atmospheric pressure and is a round number (100 kPa), the bar is a very convenient unit for many applications.

Common Applications of the Bar

The bar is a versatile unit used to measure pressure in many industrial and everyday contexts.

Common examples include:

• Automotive: Measuring tire pressure (often listed on a car's door jamb alongside PSI).
• Scuba Diving: Expressing the amount of air pressure inside diving tanks.
• Weather: Used by meteorologists for weather forecasting and reading atmospheric pressure.
• Plumbing & Pumps: Measuring water pressure in pipes and pump systems.
• Industrial: Measuring air pressure in pneumatic equipment and gas pressure in cylinders for welding.

torr to bar Conversion Table

Here are some quick reference conversions from torr (torr) to bar (bar):

This conversion in other languages

Engineering datasheets across Europe write torr to bar several different ways. The calculation is the same in every one of them.