Bar to PSIG Pressure Converter
Convert bar to pounds per square inch gauge with precision and ease
Conversion Result
Popular Bar to PSIG Conversions
This reference table provides common pressure conversions from bar to PSIG, frequently encountered in automotive, industrial, and engineering contexts throughout the UK and internationally.
| Bar | PSIG | Common Application |
|---|---|---|
| 1 bar | -0.20 PSIG | Near atmospheric pressure |
| 2 bar | 14.31 PSIG | Tyre pressure (light vehicles) |
| 2.5 bar | 21.56 PSIG | Standard tyre inflation |
| 3 bar | 28.81 PSIG | Heavy vehicle tyres |
| 5 bar | 57.82 PSIG | Pneumatic systems |
| 6 bar | 72.32 PSIG | Air compressors |
| 8 bar | 101.33 PSIG | Industrial equipment |
| 10 bar | 130.34 PSIG | Hydraulic systems |
| 15 bar | 202.86 PSIG | High-pressure applications |
| 20 bar | 275.38 PSIG | Process industries |
Conversion Formula & Steps
Bar to PSIG Formula
This formula accounts for the conversion factor where 1 bar equals approximately 14.5038 PSI (absolute), then subtracts atmospheric pressure (14.7 PSI) to obtain gauge pressure.
PSIG to Bar Formula
To reverse the conversion, add atmospheric pressure back to the gauge reading, then divide by the conversion factor.
Step-by-Step Conversion Process
- Identify your bar value: Determine the pressure measurement in bar that requires conversion.
- Multiply by conversion factor: Take your bar value and multiply it by 14.5038 to convert to PSI absolute.
- Subtract atmospheric pressure: Deduct 14.7 from the result to convert from absolute pressure to gauge pressure.
- Round appropriately: Round your final result to the required precision for your application (typically 2 decimal places).
- Verify the result: Double-check your calculation, particularly for critical safety or engineering specifications.
Worked Example
Convert 8 bar to PSIG:
- Start with 8 bar
- Multiply: 8 × 14.5038 = 116.0304 PSI
- Subtract atmospheric: 116.0304 − 14.7 = 101.3304 PSIG
- Result: 8 bar = 101.33 PSIG
Pressure Units Explained
What is Bar?
Bar is a metric unit of pressure equal to 100,000 pascals or 100 kilopascals. It represents approximately the atmospheric pressure at sea level and is widely adopted across Europe, including the UK, for measuring tyre pressure, hydraulic systems, and meteorological applications.
What is PSIG?
PSIG stands for pounds per square inch gauge, measuring pressure relative to atmospheric pressure. A reading of 0 PSIG indicates atmospheric pressure. PSIG is commonly employed in North America and various industrial sectors worldwide for gauges, compressors, and pressure vessels.
Gauge vs Absolute Pressure
Gauge pressure (PSIG) measures relative to atmospheric pressure, whilst absolute pressure (PSIA) measures relative to a perfect vacuum. The relationship is: PSIA = PSIG + atmospheric pressure (approximately 14.7 PSI at sea level).
Regional Preferences
The UK and European nations predominantly use bar for pressure measurements, especially in automotive contexts. The United States favours PSI. International engineering projects frequently require conversions between these systems to maintain consistency.
Visual Pressure Comparison
Relative Pressure Scale
Comparing equivalent pressures in bar and PSIG
Industry Applications
Automotive Sector
Tyre pressure specifications in the UK are typically expressed in bar, whilst many American vehicles and pressure gauges display PSI. Proper conversion prevents under-inflation or over-inflation, which affects fuel economy, tyre wear, and vehicle safety. Standard car tyres operate between 2.0 and 2.5 bar (14–21 PSIG).
Hydraulics & Pneumatics
Hydraulic systems in manufacturing and construction equipment operate across various pressure ranges. Accurate bar to PSIG conversion is essential when working with international equipment specifications, maintenance manuals, or when replacing components sourced from different regions. Industrial air compressors typically operate between 6 and 10 bar (72–130 PSIG).
Process Engineering
Chemical plants, refineries, and food processing facilities monitor pressure throughout production lines. Engineers must convert between bar and PSIG when interpreting sensor readings, setting safety limits, or complying with international standards. Pressure vessel specifications often require conversion between measurement systems.
HVAC Systems
Heating, ventilation, and air conditioning systems utilise pressure measurements for refrigerant charging, system diagnostics, and performance optimisation. Technicians working with equipment from various manufacturers regularly convert between bar and PSIG to achieve correct operating pressures.
Extended Conversion Table
| Bar | PSIG | Bar | PSIG |
|---|---|---|---|
| 0.5 | -7.45 | 11 | 144.84 |
| 1 | -0.20 | 12 | 159.35 |
| 1.5 | 7.06 | 13 | 173.85 |
| 2 | 14.31 | 14 | 188.35 |
| 2.5 | 21.56 | 15 | 202.86 |
| 3 | 28.81 | 16 | 217.36 |
| 4 | 43.32 | 18 | 246.37 |
| 5 | 57.82 | 20 | 275.38 |
| 6 | 72.32 | 25 | 347.90 |
| 7 | 86.83 | 30 | 420.41 |
| 8 | 101.33 | 40 | 565.45 |
| 9 | 115.83 | 50 | 710.49 |
| 10 | 130.34 | 100 | 1435.68 |
Frequently Asked Questions
Why do we subtract 14.7 when converting to PSIG?
PSIG measures gauge pressure, which is relative to atmospheric pressure. At sea level, atmospheric pressure equals approximately 14.7 PSI. When converting from bar to PSI absolute, we obtain the total pressure. Subtracting 14.7 PSI removes the atmospheric component, leaving only the gauge pressure above atmospheric conditions.
What is the difference between PSIG and PSIA?
PSIG (gauge) measures pressure relative to atmospheric pressure, whilst PSIA (absolute) measures pressure relative to a perfect vacuum. At standard atmospheric conditions, the relationship is: PSIA = PSIG + 14.7. Most pressure gauges display PSIG because they measure pressure above or below ambient atmospheric pressure.
Can I use the same conversion factor at different altitudes?
The conversion factor of 14.5038 (1 bar = 14.5038 PSI) remains constant regardless of altitude. However, atmospheric pressure varies with elevation, affecting gauge pressure readings. At higher altitudes, atmospheric pressure decreases, so the same absolute pressure yields a higher PSIG reading compared to sea level.
Which unit should I use for tyre pressure in the UK?
Vehicle manufacturers in the UK specify tyre pressures in bar, and this should be your primary reference. However, many petrol station air pumps display both bar and PSI, allowing you to use either unit. Always refer to your vehicle’s manual or the placard typically located on the driver’s door frame for correct specifications.
How precise should my pressure conversions be?
For most applications, rounding to two decimal places provides sufficient precision. Critical safety systems, scientific research, or precision engineering may require three or more decimal places. Always consider your application’s tolerance requirements and round appropriately to avoid false precision whilst maintaining necessary accuracy.
Are bar and atmosphere (atm) the same unit?
No, although they are similar in magnitude. One standard atmosphere (atm) equals 1.01325 bar or 14.696 PSI. The bar was defined as exactly 100,000 pascals for convenience, whilst the atmosphere represents actual average sea-level atmospheric pressure. For most practical purposes, they are nearly equivalent, but precise work requires distinction.