Bar to PSI Converter

Convert between bar and psi pressure units instantly

Pressure in Bar

Pressure in PSI

Popular Tyre Pressure Conversions

Conversion Result

Conversion Formula

The relationship between bar and psi is based on their respective definitions as pressure units. Both measure force per unit area, but they belong to different measurement systems.

Bar to PSI Formula

PSI = Bar × 14.5038

Multiply the pressure value in bar by 14.5038 to obtain the equivalent pressure in psi.

PSI to Bar Formula

Bar = PSI × 0.0689476

Multiply the pressure value in psi by 0.0689476 to obtain the equivalent pressure in bar.

Example Conversion:
Converting 2.5 bar to psi: 2.5 × 14.5038 = 36.26 psi
Converting 30 psi to bar: 30 × 0.0689476 = 2.07 bar

Conversion Steps

Follow these straightforward steps to convert between bar and psi accurately:

Converting Bar to PSI

1Identify the pressure value in bar that requires conversion.

2Multiply this value by the conversion factor 14.5038.

3The result represents the equivalent pressure in pounds per square inch.

4Round to two decimal places for practical applications such as tyre inflation.

Converting PSI to Bar

1Take the pressure measurement expressed in psi.

2Multiply by the conversion factor 0.0689476.

3The result gives you the pressure in bar.

4Round to one decimal place, as bar is typically expressed in tenths.

Common Bar to PSI Conversions

This reference table provides frequently used pressure conversions, particularly relevant for vehicle tyre pressures in the United Kingdom.

Bar	PSI	Common Application
1.8	26.11	Light vehicle (minimum)
2.0	29.01	Standard car tyre
2.2	31.91	Recommended front tyre
2.4	34.81	Recommended rear tyre
2.5	36.26	Popular car setting
2.6	37.71	SUV front tyre
2.8	40.61	Loaded vehicle
3.0	43.51	Van or heavy load
3.5	50.76	Commercial vehicle
4.0	58.02	Lorry tyre

Extended Conversion Table

For industrial, hydraulic, and specialised applications requiring higher pressure measurements.

Bar	PSI	Bar	PSI
0.5	7.25	6.0	87.02
1.0	14.50	7.0	101.53
1.5	21.76	8.0	116.03
2.0	29.01	9.0	130.53
2.5	36.26	10.0	145.04
3.0	43.51	15.0	217.56
3.5	50.76	20.0	290.08
4.0	58.02	25.0	362.59
4.5	65.27	30.0	435.11
5.0	72.52	50.0	725.19

Bar vs PSI Comparison

Bar (Metric Unit)

Definition: One bar equals 100,000 pascals (Pa) or 100 kilopascals (kPa).

Origin: Derived from the Greek word “baros” meaning weight. Widely adopted across Europe and metric-using nations.

Common Uses: Tyre pressure specifications, meteorology, diving depth measurements, hydraulic systems.

Atmospheric Pressure: Standard atmospheric pressure at sea level is approximately 1.013 bar.

PSI (Imperial Unit)

Definition: Pounds per square inch measures the force in pounds-force applied to one square inch of area.

Origin: Part of the Imperial measurement system, predominantly used in the United States.

Common Uses: Tyre pressure gauges in North America, compressed air systems, industrial pressure specifications.

Atmospheric Pressure: Standard atmospheric pressure at sea level is approximately 14.7 psi.

Precision Considerations

The conversion factor 14.5038 is commonly rounded to 14.5 for everyday applications. Whilst this introduces a minor deviation of approximately 0.03%, it remains acceptable for most practical purposes including tyre inflation. For scientific or engineering calculations requiring higher precision, the full conversion factor of 14.503773773 should be employed.

Visual Pressure Comparison

The following visual representation illustrates relative pressure values in both bar and psi.

1 bar = 14.50 psi

14.5

2 bar = 29.01 psi

29.01

2.5 bar = 36.26 psi

36.26

3 bar = 43.51 psi

43.51

4 bar = 58.02 psi

58.02

Tyre Pressure Guidance

Maintaining correct tyre pressure is fundamental to vehicle safety, fuel economy, and tyre longevity. In the United Kingdom, tyre pressure specifications are commonly provided in bar, though some imported vehicles may display psi values.

Typical Pressure Ranges

Passenger Cars: Generally require between 2.0 and 2.6 bar (29 to 38 psi)
Sports Utility Vehicles: Typically operate at 2.3 to 2.8 bar (33 to 41 psi)
Performance Vehicles: May specify 2.4 to 3.0 bar (35 to 44 psi) depending on load
Light Commercial Vans: Often require 2.8 to 4.0 bar (41 to 58 psi)
Bicycles: Range widely from 2.5 to 8.0 bar (36 to 116 psi) based on type

Pressure Variations

Vehicle manufacturers specify different pressures for front and rear tyres, and these recommendations change based on load conditions. A difference of merely 0.2 bar (approximately 3 psi) can noticeably affect handling, fuel consumption, and tyre wear patterns. Always consult your vehicle’s handbook or the information placard typically located on the driver’s door pillar.

Measurement System Differences

The bar belongs to the metric system and relates directly to the pascal (Pa), the SI unit of pressure. One bar precisely equals 100,000 pascals. This makes conversions to other metric units straightforward: 1 bar = 1,000 millibar = 100 kilopascals.

PSI represents an imperial measurement, calculating pressure as force (in pounds-force) distributed over area (in square inches). Whilst less common in scientific contexts, psi remains prevalent in certain industries and geographical regions, particularly North America.

The UK automotive industry predominantly uses bar for tyre pressure specifications, aligning with European standards. However, many pressure gauges display both units to accommodate various preferences and imported vehicles with psi-based recommendations.

Absolute vs Gauge Pressure

Pressure measurements can be expressed as either absolute or gauge values, and this distinction affects conversion calculations in specialised applications.

Gauge Pressure: Most tyre pressure gauges measure relative to atmospheric pressure, displaying gauge pressure (barg or psig). When your gauge reads 2.4 bar, this represents pressure above atmospheric pressure.

Absolute Pressure: Absolute pressure (bara or psia) includes atmospheric pressure in the measurement. Absolute pressure equals gauge pressure plus atmospheric pressure (approximately 1 bar or 14.7 psi at sea level).

For everyday tyre pressure conversions, gauge pressure is assumed. However, scientific and industrial applications may require absolute pressure measurements, particularly in vacuum systems, altitude-dependent calculations, or precision engineering.

Frequently Asked Questions

What is the exact conversion factor from bar to psi?

The precise conversion factor is 14.503773773. This means 1 bar equals exactly 14.503773773 psi. For most practical applications, rounding to 14.5 or 14.504 provides sufficient accuracy.

How do I convert 2.4 bar to psi?

Multiply 2.4 by 14.5038 to get 34.81 psi. This is a common tyre pressure for many passenger vehicles in the UK, particularly for rear tyres or fully loaded conditions.

Why does the UK use bar instead of psi for tyre pressure?

The United Kingdom adopted the metric system for most measurements, aligning with European standards. Bar is the metric unit for pressure, whilst psi belongs to the imperial system. This harmonisation facilitates consistency across European automotive specifications and safety standards.

Is 32 psi the same as 2.2 bar?

Very close, but not exactly. 32 psi converts to 2.206 bar, which rounds to 2.2 bar. Conversely, 2.2 bar equals 31.91 psi. This slight difference is negligible for tyre inflation purposes.

Can I use a psi gauge on a car with bar specifications?

Absolutely. Simply convert the manufacturer’s recommended bar pressure to psi before inflating. Many modern pressure gauges display both units simultaneously, eliminating the need for manual conversion.

What happens if I confuse bar and psi readings?

Since 1 bar equals approximately 14.5 psi, confusing these units would result in severely under-inflated tyres. For example, inflating to 2.4 psi instead of 2.4 bar would leave your tyres at only 16% of the correct pressure, creating dangerous driving conditions and rapid tyre damage.

Are bar and atmosphere (atm) the same?

No, though they’re similar. Standard atmospheric pressure (1 atm) equals 1.01325 bar or 14.696 psi. Bar is slightly lower than atmosphere, but the difference is small enough that 1 bar provides a convenient approximation of sea-level atmospheric pressure.

How precise should my pressure measurements be?

For vehicle tyres, precision to 0.1 bar (approximately 1.5 psi) suffices. More critical applications such as racing tyres, precision machinery, or scientific experiments may require accuracy to 0.01 bar or better. Quality digital gauges typically provide this level of precision.

Do temperature changes affect bar and psi equally?

Yes. Both units measure the same physical property (pressure), so temperature-induced pressure changes affect them proportionally. Tyre pressure typically increases by approximately 0.1 bar (1.5 psi) for every 10°C temperature rise, regardless of which unit you’re measuring.

What pressure unit do professional mechanics in the UK use?

UK mechanics predominantly work with bar for tyre pressures, aligning with vehicle manufacturer specifications and European standards. However, they maintain familiarity with psi conversions for imported vehicles and certain specialised equipment that may use imperial measurements.