Psi vs. Bar — What's the Difference?
By Fiza Rafique & Urooj Arif — Updated on April 15, 2024
Psi (pounds per square inch) and bar are both units of pressure, but psi is primarily used in the U.S., while bar is common in Europe and in the scientific community globally.
Difference Between Psi and Bar
Table of Contents
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Key Differences
Psi measures pressure as one pound-force per square inch of area, a unit derived from the imperial system. Whereas, bar measures pressure as one bar equal to exactly 100,000 pascals or roughly the atmospheric pressure at sea level.
In automotive applications, psi is often used to measure tire pressure in the United States. On the other hand, in Europe and many other parts of the world, tire pressure is typically measured in bar.
Psi is widely used in various industries and engineering fields in the U.S., such as in hydraulic systems and air compressors. While, bar is frequently utilized in meteorology, oceanography, and scuba diving internationally.
For scientific calculations, psi is not as commonly used due to its basis in the imperial system, which is less coherent with the SI (International System of Units). Whereas, bar, while not an SI unit, closely relates to the pascal, making it more convenient for international scientific communication.
When converting between the two, 1 psi is approximately equal to 0.0689 bar, highlighting a direct mathematical relationship but also the inconvenience of conversion due to non-rounded numbers.
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Comparison Chart
System of Units
Imperial system.
Metric system (closely related).
Common Usage
U.S. industries: automotive, engineering.
European and global usage: science, meteorology.
Numerical Relation
1 psi = 0.0689 bar.
1 bar = 14.5038 psi.
Scientific Relevance
Less favored in global scientific calculations.
More aligned with international scientific standards.
Practical Examples
Used in measuring air pressure in tires in the U.S.
Used in atmospheric pressure readings and scuba diving.
Compare with Definitions
Psi
Indicates force per unit area.
Hydraulic systems often operate at pressures of thousands of psi.
Bar
Not an SI unit, but closely related.
In scientific communication, pressure is often converted to bars.
Psi
Common in everyday usage in the U.S.
Air compressors are typically rated in psi.
Bar
Equals 100,000 pascals.
Many industrial systems are calibrated in bar for international use.
Psi
Not part of the SI unit system.
Scientific papers rarely use psi for pressure measurements.
Bar
Metric unit of pressure, close to the atmosphere at sea level.
The bar is commonly used to measure atmospheric pressure.
Psi
Unit of pressure in the imperial system.
The recommended tire pressure for most cars is about 32 psi.
Bar
Used globally, especially in scientific fields.
Ocean depths are often measured in bars due to the intuitive scale.
Psi
Often used in engineering contexts.
The structural stress for these materials is tested at 120 psi.
Bar
Common in various applications outside the U.S.
European scuba divers monitor tank pressures in bars.
Psi
The 23rd letter of the Greek alphabet. See Table at alphabet.
Bar
A long rigid piece of wood, metal, or similar material, typically used as an obstruction, fastening, or weapon
Bars on the windows
An iron bar
Psi
Parapsychological phenomena or abilities considered as a group.
Bar
A counter in a pub, restaurant, or cafe across which drinks or refreshments are served
Standing at the bar
Psi
(countable) The twenty-third letter of Classical and Modern Greek and the twenty-fifth letter of Old and Ancient Greek.
Bar
A barrier or restriction to an action or advance
Political differences are not necessarily a bar to a good relationship
Psi
A form of psychic energy.
Bar
Any of the short sections or measures, typically of equal time value, into which a piece of music is divided, shown on a score by vertical lines across the stave
The opening bars of the first hymn
Psi
A unit of pressure
Bar
A partition in a court room, now usually notional, beyond which most people may not pass and at which an accused person stands
The prisoner at the bar
Psi
The 23rd letter of the Greek alphabet
Bar
The profession of barrister
His dismissal from the Singapore Bar
Bar
A unit of pressure equivalent to a hundred thousand newtons per square metre or approximately one atmosphere.
Bar
Fasten (something, especially a door or window) with a bar or bars
She bolted and barred the door
Bar
Prevent or prohibit (someone) from doing something or from going somewhere
Journalists had been barred from covering the elections
Bar
Mark (something) with bars or stripes
His face was barred with light
Bar
Except for
His kids were all gone now, bar one
Bar
A relatively long, straight, rigid piece of solid material used as a fastener, support, barrier, or structural or mechanical member.
Bar
A solid oblong block of a substance or combination of ingredients, such as soap or candy.
Bar
A usually rectangular slice of any of various flat baked confections that are typically dense in texture.
Bar
A rectangular block of a precious metal.
Bar
See horizontal bar.
Bar
A horizontal rod that marks the height to be cleared in high jumping or pole vaulting.
Bar
A standard, expectation, or degree of requirement
A leader whose example set a high bar for others.
Bar
Something that impedes or prevents action or progress
A poor education was a bar to his ambitions.
Bar
A ridge, as of sand or gravel, on a shore or streambed, that is formed by the action of tides or currents.
Bar
A narrow marking, as a stripe or band.
Bar
A narrow metal or embroidered strip worn on a military uniform indicating rank or service.
Bar
Chiefly British A small insignia worn on a military decoration indicating that it has been awarded an additional time.
Bar
(Heraldry) A pair of horizontal parallel lines drawn across a shield.
Bar
The nullification, defeat, or prevention of a claim or action.
Bar
The process by which nullification, defeat, or prevention is achieved.
Bar
The railing in a courtroom separating the participants in a legal proceeding from the spectators.
Bar
A court or courtroom.
Bar
Attorneys considered as a group. Used with the.
Bar
The profession of law. Used with the.
Bar
A vertical line drawn through a staff to mark off a measure.
Bar
A measure.
Bar
Variant of barre.
Bar
A counter at which drinks, especially alcoholic drinks, and sometimes food, are served.
Bar
An establishment or room having such a counter.
Bar
A unit of pressure equal to one million (106) dynes per square centimeter.
Bar
To fasten securely with a long, straight, rigid piece of material
Barred the gate.
Bar
To shut in or confine
Barred themselves in the basement.
Bar
To obstruct or impede; block
Barred the access route.
Bar
To keep out; exclude
Tourists are barred from this room.
Bar
To prohibit or prevent (someone) from doing something
Failing the eye exam barred him from driving.
Bar
To prohibit (an action)
The state bars the dumping of waste in the river.
Bar
(Law) To nullify, defeat, or prevent (a claim or action).
Bar
To rule out; except
Can we bar the possibility of foul play?.
Bar
To mark with stripes or bands.
Bar
Chiefly British Except for; excluding
This was your best performance, bar none.
Bar
A solid, more or less rigid object of metal or wood with a uniform cross-section smaller than its length.
The window was protected by steel bars.
Bar
A solid metal object with uniform (round, square, hexagonal, octagonal or rectangular) cross-section; in the US its smallest dimension is 4 inch or greater, a piece of thinner material being called a strip.
Ancient Sparta used iron bars instead of handy coins in more valuable alloy, to physically discourage the use of money.
We are expecting a carload of bar tomorrow.
Bar
A cuboid piece of any solid commodity.
Bar of chocolate
Bar of soap
Bar
A broad shaft, band, or stripe.
A bar of light
A bar of colour
Bar
A long, narrow drawn or printed rectangle, cuboid or cylinder, especially as used in a bar code or a bar chart.
Bar
(typography) Any of various lines used as punctuation or diacritics, such as the pipe ⟨{{!}}⟩, fraction bar (as in 12), and strikethrough (as in Ⱥ), formerly including oblique marks such as the slash.
Bar
(mathematics) The sign indicating that the characteristic of a logarithm is negative, conventionally placed above the digit(s) to show that it applies to the characteristic only and not to the mantissa.
Bar
(physics) A similar sign indicating that the charge on a particle is the negative of its usual value (and that consequently the particle is in fact an antiparticle).
Bar
A business selling alcoholic drinks for consumption on the premises, or the premises themselves; a public house.
The street was lined with all-night bars.
Bar
The counter of such premises.
Step up to the bar and order a drink.
Bar
A counter, or simply a cabinet, from which alcoholic drinks are served in a private house or a hotel room.
Bar
, juice bar, etc.}} Premises or a counter serving any type of beverage.
Bar
An establishment where alcohol and sometimes other refreshments are served.
Bar
An informal establishment selling food to be consumed on the premises.
A burger bar
A local fish bar
Bar
An establishment offering cosmetic services.
A nail bar; a brow bar
Bar
An official order or pronouncement that prohibits some activity.
The club has lifted its bar on women members.
Bar
Anything that obstructs, hinders, or prevents; an obstruction; a barrier.
Bar
A metasyntactic variable representing an unspecified entity, often the second in a series, following foo.
Suppose we have four objects, foo, bar, baz and quux.
Bar
A dividing line (physical or notional) in the chamber of a legislature beyond which only members and officials may pass.
Bar
The railing surrounding the part of a courtroom in which the judges, lawyers, defendants and witnesses stay.
Bar
The bar exam, the legal licensing exam.
He's studying hard to pass the Bar this time; he's failed it twice before.
Bar
Collectively, lawyers or the legal profession; specifically applied to barristers in some countries, but including all lawyers in others.
He was called to the bar, he became a barrister.
Bar
One of an array of bar-shaped symbols that display the level of something, such as wireless signal strength or battery life remaining.
I don't have any bars in the middle of this desert.
Bar
(music) A vertical line across a musical staff dividing written music into sections, typically of equal durational value.
Bar
(music) One of those musical sections.
Bar
(sports) A horizontal pole that must be crossed in the high jump and pole vault.
Bar
(metaphorical) Any level of achievement regarded as a challenge to be overcome.
Bar
The crossbar.
Bar
(backgammon) The central divider between the inner and outer table of a backgammon board, where stones are placed if they are hit.
Bar
An addition to a military medal, on account of a subsequent act.
Bar
A linear shoaling landform feature within a body of water.
Bar
A ridge or succession of ridges of sand or other substance, especially a formation extending across the mouth of a river or harbor or off a beach, and which may obstruct navigation. (FM 55-501).
Bar
(heraldry) One of the ordinaries in heraldry; a diminutive of a fess.
Bar
A city gate, in some British place names.
Bar
(mining) A drilling or tamping rod.
Bar
(mining) A vein or dike crossing a lode.
Bar
(architecture) A gatehouse of a castle or fortified town.
Bar
(farriery) The part of the crust of a horse's hoof which is bent inwards towards the frog at the heel on each side, and extends into the centre of the sole.
Bar
The space between the tusks and grinders in the upper jaw of a horse, in which the bit is placed.
Bar
(slang) A measure of drugs, typically one ounce.
Bar
A non-SI unit of pressure equal to 100,000 pascals, approximately equal to atmospheric pressure at sea level.
Bar
(transitive) To obstruct the passage of (someone or something).
Our way was barred by a huge rockfall.
Bar
(transitive) To prohibit.
I couldn't get into the nightclub because I had been barred.
Bar
(transitive) To lock or bolt with a bar.
Bar the door
Bar
To imprint or paint with bars, to stripe.
Bar
Except, other than, besides.
He invited everyone to his wedding bar his ex-wife.
Bar
(horse racing) Denotes the minimum odds offered on other horses not mentioned by name.
Leg At Each Corner is at 3/1, Lost My Shirt 5/1, and it's 10/1 bar.
Bar
A piece of wood, metal, or other material, long in proportion to its breadth or thickness, used as a lever and for various other purposes, but especially for a hindrance, obstruction, or fastening; as, the bars of a fence or gate; the bar of a door.
Thou shalt make bars of shittim wood.
Bar
An indefinite quantity of some substance, so shaped as to be long in proportion to its breadth and thickness; as, a bar of gold or of lead; a bar of soap.
Bar
Anything which obstructs, hinders, or prevents; an obstruction; a barrier.
Must I new bars to my own joy create?
Bar
A bank of sand, gravel, or other matter, esp. at the mouth of a river or harbor, obstructing navigation.
Bar
Any railing that divides a room, or office, or hall of assembly, in order to reserve a space for those having special privileges; as, the bar of the House of Commons.
Bar
The railing that incloses the place which counsel occupy in courts of justice. Hence, the phrase at the bar of the court signifies in open court.
Bar
Any tribunal; as, the bar of public opinion; the bar of God.
Bar
A barrier or counter, over which liquors and food are passed to customers; hence, the portion of the room behind the counter where liquors for sale are kept.
Bar
An ordinary, like a fess but narrower, occupying only one fifth part of the field.
Bar
A broad shaft, or band, or stripe; as, a bar of light; a bar of color.
Bar
A vertical line across the staff. Bars divide the staff into spaces which represent measures, and are themselves called measures.
Bar
The space between the tusks and grinders in the upper jaw of a horse, in which the bit is placed.
Bar
A drilling or tamping rod.
Bar
A gatehouse of a castle or fortified town.
Bar
To fasten with a bar; as, to bar a door or gate.
Bar
To restrict or confine, as if by a bar; to hinder; to obstruct; to prevent; to prohibit; as, to bar the entrance of evil; distance bars our intercourse; the statute bars my right; the right is barred by time; a release bars the plaintiff's recovery; - sometimes with up.
He barely looked the idea in the face, and hastened to bar it in its dungeon.
Bar
To except; to exclude by exception.
Nay, but I bar to-night: you shall not gauge meBy what we do to-night.
Bar
To cross with one or more stripes or lines.
For the sake of distinguishing the feet more clearly, I have barred them singly.
Bar
A room or establishment where alcoholic drinks are served over a counter;
He drowned his sorrows in whiskey at the bar
Bar
A counter where you can obtain food or drink;
He bought a hot dog and a coke at the bar
Bar
A rigid piece of metal or wood; usually used as a fastening or obstruction or weapon;
There were bars in the windows to prevent escape
Bar
Musical notation for a repeating pattern of musical beats;
The orchestra omitted the last twelve bars of the song
Bar
An obstruction (usually metal) placed at the top of a goal;
It was an excellent kick but the ball hit the bar
Bar
The act of preventing;
There was no bar against leaving
Money was allocated to study the cause and prevention of influenza
Bar
(meteorology) a unit of pressure equal to a million dynes per square centimeter;
Unfortunately some writers have used bar for one dyne per square centimeter
Bar
A submerged (or partly submerged) ridge in a river or along a shore;
The boat ran aground on a submerged bar in the river
Bar
The body of individuals qualified to practice law in a particular jurisdiction;
He was admitted to the bar in New Jersey
Bar
A block of solid substance (such as soap or wax);
A bar of chocolate
Bar
A portable .30 caliber magazine-fed automatic rifle operated by gas pressure; used by United States troops in World War I and in World War II and in the Korean War
Bar
A horizontal rod that serves as a support for gymnasts as they perform exercises
Bar
A heating element in an electric fire;
An electric fire with three bars
Bar
(law) a railing that encloses the part of the courtroom where the judges and lawyers sit and the case is tried;
Spectators were not allowed past the bar
Bar
Prevent from entering; keep out;
He was barred from membership in the club
Bar
Render unsuitable for passage;
Block the way
Barricade the streets
Stop the busy road
Bar
Expel, as if by official decree;
He was banished from his own country
Bar
Secure with, or as if with, bars;
He barred the door
Common Curiosities
Which industries prefer psi?
Psi is preferred in U.S.-based automotive, aeronautics, and engineering industries.
How does bar relate to atmospheric pressure?
One bar is approximately equal to the atmospheric pressure at sea level.
Is psi or bar more accurate?
Neither is more accurate; accuracy depends on the measurement device, not the unit.
What is psi used for?
Psi is used for measuring pressure in various systems like tires, hydraulics, and air compressors in the U.S.
Why is bar used in scientific research?
Bar is used because it closely aligns with the SI units, facilitating clearer international communication.
Can psi and bar be used interchangeably?
While they measure the same quantity (pressure), conversion is required, as they belong to different measurement systems.
What are typical pressure readings in bar for scuba diving?
Scuba tanks are often filled to about 200 bar.
What does a reading of 1 bar indicate?
A reading of 1 bar indicates a pressure close to that of the Earth's atmospheric pressure at sea level.
What psi levels are considered high in industrial settings?
Pressures over 3,000 psi are considered high in many industrial applications.
How do you convert psi to bar?
To convert psi to bar, multiply the psi value by 0.06895.
Which unit is more common in weather forecasting?
Bar and its derivative, the millibar, are commonly used in weather forecasting globally.
Why isn't psi used globally?
Psi is based on the imperial system, which is less universally adopted than the metric system.
How can understanding these units benefit someone?
Understanding these units can help in professions involving engineering, meteorology, and other sciences, enhancing accuracy in international collaboration.
Is there a trend in changing from psi to bar in any industry?
There is a trend towards using metric units like bar in industries that operate internationally to standardize measurements.
What is a common use of bar in everyday life?
Bar is used to measure tire pressure and is noted on weather stations.
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Written by
Fiza RafiqueFiza Rafique is a skilled content writer at AskDifference.com, where she meticulously refines and enhances written pieces. Drawing from her vast editorial expertise, Fiza ensures clarity, accuracy, and precision in every article. Passionate about language, she continually seeks to elevate the quality of content for readers worldwide.
Co-written by
Urooj ArifUrooj is a skilled content writer at Ask Difference, known for her exceptional ability to simplify complex topics into engaging and informative content. With a passion for research and a flair for clear, concise writing, she consistently delivers articles that resonate with our diverse audience.
