Convert Pressure from pounds per square inch to bar (psi to bar)

Pound per Square Inch to Bar Conversion Formula

To convert a pressure from pounds per square inch (psi) to bar, multiply by 0.0689476 — or, equivalently, divide by 14.5038.

• bar = psi × 0.0689476
• bar = psi ÷ 14.5038

The bar is defined as exactly 100,000 Pa and the psi is 6,894.76 Pa, so one psi is 0.0689476 bar. The relationship worth memorizing runs the other way: 1 bar ≈ 14.5 psi, and one standard atmosphere is 14.696 psi = 1.01325 bar — which is why "about 1 bar" and "about 15 psi" both serve as shorthand for atmospheric pressure.

Step-by-Step Example

A US-spec scuba cylinder is filled to 3,000 psi and a European dive computer expects the reading in bar:

1. Take the pressure: 3,000 psi
2. Multiply by 0.0689476: 3,000 × 0.0689476 = 206.8 bar

That is the familiar "200 bar" class of cylinder — the two markets rate the same tank in different units.

Quick Reference Table

barg, bara and the Compressed-Air Convention

Industrial pneumatics is where this conversion earns its keep, and it is also where a quiet suffix convention matters. European compressed-air systems are specified in barg — bar gauge — so a "7 bar network" and a "100 psi shop line" are the same installation (7 barg = 101.5 psig). Process engineering documents sometimes switch to bara (bar absolute) for thermodynamic work, and the difference between the two is almost exactly one atmosphere. The arithmetic on this page converts the unit, not the reference frame: 100 psig is 6.89 barg, and only becomes about 7.90 bara after adding the atmosphere back. Scuba deserves its own caution in the same spirit — cylinder working pressures are gauge figures, but the gas planning math (how many liters of breathable air a 12 L / 200 bar tank holds) silently treats them as absolute multiples, which works only because 1 atm is small against 200 bar. At low pressures that shortcut stops being harmless.

How many pounds per square inch are in one bar? One bar (bar) contains 14.503768078 pounds per square inch (psi) — the inverse of the factor above. Multiplying by 0.068947600004501395751 takes you from pounds per square inch to bar; multiplying by 14.503768078 brings you back.

Put in words: one pound per square inch equals 0.068947600004501395751 bar, so the pound per square inch 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 pound per square inch (psi)?

A pound per square inch (PSI) is a unit of pressure commonly used in the imperial system (which is standard in the United States).

It measures the amount of force applied over a single square inch of area.

Common Examples of PSI (Where is PSI Used?)

PSI is a critical measurement for safety and performance in many common items, including:

• Vehicle Tires: Proper tire pressure (PSI) ensures optimal handling, fuel efficiency, and tire life. You can find the recommended level on a sticker inside the driver's door.

• Home Water Pressure: Affects everything from shower performance to how well appliances like dishwashers and washing machines function.

• Sports Equipment: Items like footballs, basketballs, and soccer balls require a specific PSI to perform correctly and safely.

• Tools: Air compressors, pressure washers, and paint sprayers all have specific PSI ratings for safe and effective operation.

Converting PSI to Metric Units like Pascals and Bar

While PSI is standard in the imperial system, scientific and international contexts use metric (SI) units like the Pascal (Pa) and the bar.

• PSI to Pascal (Pa): The official SI unit for pressure.
  1 PSI ≈ 6,894.76 Pascals (or 6.895 kilopascals, kPa).

• PSI to Bar: A common unit in automotive and weather contexts. 1 bar is roughly equal to atmospheric pressure at sea level.
  1 PSI ≈ 0.0689 bar.

Understanding the Types of PSI: PSIG, PSIA, and PSID

The term "PSI" can be specified further to give more context:

• PSIG (Pound-force per square inch gauge): Measures pressure relative to the surrounding atmospheric pressure. This is the most common measurement, used by a standard tire gauge.

• PSIA (Pound-force per square inch absolute): Measures pressure relative to a perfect vacuum (absolute zero pressure).
  The formula is: PSIA = PSIG + local atmospheric pressure.

• PSID (Pound-force per square inch differential): Measures the difference in pressure between two separate points in a system, such as across a filter or valve.

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.

pound per square inch to bar Conversion Table

Here are some quick reference conversions from pound per square inch (psi) to bar (bar):

This conversion in other languages

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