Convert Pressure from bar to torr

Bar to Torr Conversion Formula

To convert a pressure from bar to torr, multiply by 750.062.

• torr = bar × 750.062

The factor comes from the two definitions: a bar is exactly 100,000 Pa, a torr is exactly 101,325/760 Pa (≈133.322 Pa), and dividing gives 750.0617. The nearly-round result invites the useful approximation 1 bar ≈ 750 torr, good to 0.01%.

The anchor tying everything together: 1.01325 bar = 760 torr exactly — both are definitions of the standard atmosphere.

Step-by-Step Example

A process chamber is backfilled to 0.4 bar and the recipe sheet is written in torr:

1. Take the pressure: 0.4 bar
2. Multiply by 750.062: 0.4 × 750.062 = 300 torr

Quick Reference Table

Crossing From Gauge Country Into Vacuum Country

Bar and torr rarely share a document, because they serve opposite ends of the pressure axis — bar describes pressures at and above the atmosphere, torr describes the road down to nothing. The conversion appears exactly at the border: venting a vacuum system back to atmosphere (1.013 bar arriving as 760 torr on the chamber gauge), specifying a backfill or partial-pressure step, or translating a European pump datasheet (ultimate pressure in mbar) for an American process engineer who thinks in torr. In that last case the neater bridge is one step smaller: 1 mbar = 0.750 torr, the same factor with the decimal shifted.

One frame-of-reference note. Vacuum figures in torr are absolute pressures — zero torr is a perfect vacuum, not the room. Bar figures from compressors and pipe gauges are usually gauge readings. Converting a gauge bar figure into torr without adding the atmosphere first produces a number that means nothing in a vacuum context; the 750.062 belongs to absolute-to-absolute conversions.

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

Put in words: one bar equals 750.0616827041697508 torr, so the bar is the larger 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 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.

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

bar to torr Conversion Table

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

This conversion in other languages

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