What is 2.5 bar in PSI?

2.5 bar = 36.3 PSI. This is typical for SUVs, vans, and high-performance cars.

How many bar is atmospheric pressure?

1.01325 bar exactly at sea level. Often rounded to 1 bar for practical calculations.

What is a good PSI for car tires?

Standard car tire pressure : 32-35 PSI (when cold) Always check your specific vehicle : Driver's door jamb sticker (most reliable) Owner's manual Fuel filler door (some vehicles) By vehicle type : Compact cars: 30-33 PSI Sedans: 32-35 PSI SUVs/Light trucks: 35-45 PSI High-performance: 36-40 PSI Important : Check when tires are COLD (before driving). Tire pressure increases 4-6 PSI after driving. Convert to your region: PSI to Bar →

What does PSIG vs PSIA mean?

PSIG (Pounds per Square Inch Gauge) : Pressure relative to atmospheric pressure 0 PSIG = atmospheric pressure (14.7 PSIA at sea level) What most pressure gauges show Used for tires, compressors, hydraulics PSIA (Pounds per Square Inch Absolute) : Pressure relative to perfect vacuum 0 PSIA = absolute vacuum 14.7 PSIA = atmospheric pressure at sea level Used in scientific/engineering calculations Conversion : PSIA = PSIG + 14.7 (at sea level) Example : 32 PSIG tire pressure = 46.7 PSIA total pressure

What is 100 PSI in bar and kPa?

100 PSI equals : 6.89 bar 689.5 kPa (kilopascals) 0.689 MPa (megapascals) Quick conversions : 100 PSI to Bar → 100 PSI to kPa → Context : 100 PSI is typical for: Heavy-duty air compressor output Semi-truck tire pressure Pneumatic tool operating pressure

Is 40 PSI good tire pressure?

40 PSI can be correct depending on your vehicle : Good for : Large SUVs and trucks Some high-performance vehicles Vehicles when fully loaded Too high for : Most passenger cars (typically 32-35 PSI) Compact cars (typically 30-33 PSI) How to know : Check driver's door jamb sticker Consult owner's manual Never rely on tire sidewall (that's MAX pressure) Effects of overinflation : Harsher ride Reduced traction Uneven tire wear (center wears faster) Always check : When tires are COLD, before driving.

How many PSI in 1 atmosphere?

1 atmosphere (atm) = 14.6959 PSI (approximately 14.7 PSI) Standard atmospheric pressure at sea level : 14.696 PSI (PSIA) 101.325 kPa 1.01325 bar 760 mmHg / 760 Torr 29.92 inHg Altitude effects : Sea level: 14.7 PSI Denver (5,280 ft): ~12.1 PSI 10,000 ft: ~10.1 PSI Convert Atmosphere to PSI →

What PSI should I set my air compressor to?

Typical settings : General Shop Use : 90-100 PSI Most pneumatic tools operate best at 90 PSI Allows for pressure drop in hoses Specific Applications : Impact wrench: 90 PSI Nail gun: 70-120 PSI (tool dependent) Paint sprayer: 25-50 PSI Tire inflation: 30-40 PSI Sandblasting: 80-100 PSI Air brush: 15-30 PSI Compressor tank pressure : 125-150 PSI (maximum) Compressor cuts off at max (e.g., 135 PSI) Compressor cuts on when drops (e.g., 100 PSI) Set regulator to desired tool pressure (e.g., 90 PSI) Pro tip : Set higher tank pressure, use regulator for precise tool pressure.

Why is PSI used instead of bar in the US?

Historical reasons : Imperial system was established before metric US industry standardized on PSI in early 1900s Extensive infrastructure built around imperial units Practical resistance to change : All existing gauges, equipment use PSI Workforce trained in PSI Replacement costs would be enormous Cultural familiarity Current situation : US is primary country still using PSI Scientific/international work uses metric (bar, kPa) Some US industries use both systems For travelers : Most modern tire gauges show both PSI and bar. Convert between systems: PSI to Bar →

Pressure Unit Converter

Convert between different units of pressure

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About Pressure Conversions

Convert between different units of pressure

Convert between 17 different pressure units including Pascal, Kilopascal, Megapascal, Hectopascal, Bar, and more. Our free online converter provides instant, accurate conversions with formulas, examples, and conversion tables.

Quick Start: Pressure Conversions

Convert between 17+ pressure units instantly. Perfect for automotive (tire pressure), HVAC, weather forecasting, medical equipment, hydraulics, pneumatics, and engineering applications.

Most Popular Conversions:

PSI to Bar - Tire pressure & hydraulics
Bar to PSI - European to US specs
Pascal to PSI - Scientific to practical
Kilopascal to PSI - Metric to imperial
mmHg to PSI - Medical to engineering

Understanding Pressure Conversions

Pressure is force applied over an area—the amount of force distributed per unit of surface. It's fundamental in engineering, meteorology, medicine, automotive, HVAC, hydraulics, pneumatics, and countless industrial applications.

Why Pressure Conversion Matters

Automotive & Transportation: Tire pressure specifications vary by region—US uses PSI, Europe uses bar, Asia often uses kPa. Correct tire pressure is critical for safety, fuel efficiency, and tire longevity.

HVAC & Refrigeration: Air conditioning systems, refrigeration, and climate control use various pressure units. Technicians must convert between PSI, bar, and kPa when working with international equipment.

Weather & Aviation: Weather reports use millibars (mbar) or hectopascals (hPa) for atmospheric pressure. Aviation altimeters use inches of mercury (inHg). Understanding conversions helps interpret forecasts and flight conditions.

Medical & Healthcare: Blood pressure is measured in mmHg (millimeters of mercury). Medical gases and equipment may use PSI, bar, or kPa depending on manufacturer and region.

Engineering & Manufacturing: Hydraulic systems, pneumatic tools, pressure vessels, and industrial processes require precise pressure specifications. Engineers must convert between units when working with international standards and equipment.

Common Pressure Units Explained

SI (Metric) Units

Pascal (Pa) - Base Unit: The fundamental SI unit of pressure. 1 Pascal = 1 Newton per square meter (N/m²). Very small for practical applications, so kilo- and mega- prefixes are common.

Kilopascal (kPa): 1,000 Pascals. Standard metric unit for automotive tire pressure, HVAC systems, and general engineering. Common in Canada, Australia, Asia.

Megapascal (MPa): 1,000,000 Pascals (1,000 kPa). Used for high-pressure applications like hydraulic systems, material testing, and industrial processes.

Hectopascal (hPa): 100 Pascals. Identical to millibar (mbar). Standard unit for weather reports and aviation worldwide. Sea-level atmospheric pressure ≈ 1013 hPa.

Bar: 100,000 Pascals (100 kPa). Very close to atmospheric pressure at sea level. Widely used in Europe for tire pressure, HVAC, hydraulics, and industrial applications.

Millibar (mbar): 1/1000th of a bar (100 Pascals). Identical to hectopascal. Used in meteorology and aviation for atmospheric pressure readings.

Imperial / US Customary Units

PSI (Pounds per Square Inch): The most common pressure unit in the United States. Ubiquitous in automotive (tire pressure), pneumatic tools, air compressors, plumbing, and HVAC.

KSI (Kilopounds per Square Inch): 1,000 PSI. Used for very high pressures in structural engineering, material testing, and heavy industrial applications.

Atmospheric Pressure Units

Atmosphere (atm): Standard atmospheric pressure at sea level (101,325 Pa ≈ 14.7 PSI ≈ 1.013 bar). Used as a reference in chemistry, physics, and diving.

Technical Atmosphere (at): 1 kilogram-force per square centimeter (kgf/cm²). Historical metric unit, still used in some engineering contexts.

Mercury & Water Column

Millimeter of Mercury (mmHg): Pressure exerted by 1mm column of mercury. Standard unit for blood pressure and medical applications. Also called "Torr" in scientific contexts.

Torr: Defined as 1/760th of standard atmospheric pressure. Exactly equal to mmHg. Used in vacuum technology and scientific applications.

Inch of Mercury (inHg): Pressure exerted by 1 inch column of mercury. Used in US weather reports, aviation altimeters, and barometric pressure.

Millimeter of Water Column (mmH₂O): Pressure exerted by 1mm column of water. Used for low-pressure applications like ventilation, gas supply, and draft measurement.

Inch of Water Column (inH₂O): Pressure exerted by 1 inch column of water. Common in HVAC for measuring static pressure in ducts.

Kilogram-force Units

Kilogram-force per Square Centimeter (kgf/cm²): Force of 1 kilogram-mass under standard gravity on 1 cm². Common in older metric engineering literature and some industrial contexts.

Kilogram-force per Square Meter (kgf/m²): Force of 1 kilogram-mass under standard gravity on 1 m². Rarely used but appears in some technical specifications.

Conversion Quick Reference

Common Conversions

From	To	Multiply By	Example
PSI	Bar	0.0689476	30 psi = 2.07 bar
Bar	PSI	14.5038	2 bar = 29.0 psi
PSI	kPa	6.89476	50 psi = 344.7 kPa
kPa	PSI	0.145038	200 kPa = 29.0 psi
Bar	kPa	100	2.5 bar = 250 kPa
kPa	Bar	0.01	350 kPa = 3.5 bar
Atm	PSI	14.6959	1 atm = 14.7 psi
mmHg	PSI	0.0193368	120 mmHg = 2.32 psi

Atmospheric Pressure at Sea Level

Standard atmosphere (various units):

101,325 Pascals (Pa)
101.325 Kilopascals (kPa)
0.101325 Megapascals (MPa)
1,013.25 Hectopascals (hPa)
1,013.25 Millibars (mbar)
1.01325 Bar
14.6959 PSI
1 Atmosphere (atm)
1.03323 Technical atmospheres (at)
760 Torr
760 mmHg
29.92 inHg
10,332 mmH₂O
406.8 inH₂O

Within Metric System

From	To	Multiply By
MPa	kPa	1,000
kPa	Pa	1,000
Bar	kPa	100
hPa	Pa	100
mbar	hPa	1 (identical)

Practical Pressure Examples

Automotive & Tires

Typical Tire Pressures (passenger cars):

Standard: 32-35 PSI (2.2-2.4 bar / 220-240 kPa)
High-performance: 36-40 PSI (2.5-2.8 bar / 250-280 kPa)
Light trucks/SUVs: 35-45 PSI (2.4-3.1 bar / 240-310 kPa)
Underinflated warning: <25 PSI (<1.7 bar / <170 kPa)
Race cars (cold): 25-30 PSI (1.7-2.1 bar)
Race cars (hot): 35-40 PSI (2.4-2.8 bar)

Bicycle Tires:

Road bike: 80-130 PSI (5.5-9.0 bar)
Mountain bike: 25-50 PSI (1.7-3.4 bar)
Hybrid bike: 50-70 PSI (3.4-4.8 bar)

Weather & Atmospheric Pressure

Barometric Pressure (Sea Level):

Standard atmosphere: 1013.25 mbar (29.92 inHg / 14.7 PSI)
High pressure system: 1020-1040 mbar (30.1-30.7 inHg)
Low pressure system: 980-1000 mbar (28.9-29.5 inHg)
Strong low pressure: 950-980 mbar (28.1-28.9 inHg)
Hurricane/Typhoon center: 880-950 mbar (26.0-28.1 inHg)
Record low (Typhoon Tip): 870 mbar (25.7 inHg)

Altitude Effects:

Sea level: 1013 mbar
5,000 ft (1,524 m): 843 mbar
10,000 ft (3,048 m): 697 mbar
18,000 ft (5,486 m): 500 mbar
29,029 ft (Mt. Everest): 337 mbar

Medical Applications

Blood Pressure (mmHg):

Normal: 120/80 mmHg (systolic/diastolic)
Elevated: 120-129 / <80 mmHg
High (Stage 1): 130-139 / 80-89 mmHg
High (Stage 2): ≥140 / ≥90 mmHg
Hypertensive crisis: >180 / >120 mmHg
Low (hypotension): <90 / <60 mmHg

Medical Gas Cylinders:

Oxygen cylinder (full): 2,000-2,200 PSI (137-152 bar)
Compressed air (hospital): 50 PSI (3.4 bar)
CPAP machines: 4-20 cmH₂O (0.06-0.3 PSI)

HVAC & Refrigeration

Air Conditioning (R-410A):

Low side (suction): 118-138 PSI (8.1-9.5 bar)
High side (discharge): 250-450 PSI (17.2-31.0 bar)

Refrigeration Systems:

Walk-in cooler: 20-40 PSI (1.4-2.8 bar)
Walk-in freezer: 0-20 PSI (0-1.4 bar)

HVAC Duct Pressure:

Residential ductwork: 0.1-0.5 inH₂O (25-125 Pa)
Commercial HVAC: 1-3 inH₂O (250-750 Pa)

Industrial & Hydraulics

Compressed Air:

Workshop tools: 90-120 PSI (6.2-8.3 bar)
Pneumatic systems: 80-100 PSI (5.5-6.9 bar)
Air compressor max: 125-175 PSI (8.6-12.1 bar)

Hydraulic Systems:

Mobile hydraulics: 2,000-3,000 PSI (138-207 bar)
Industrial hydraulics: 1,000-5,000 PSI (69-345 bar)
High-pressure hydraulics: 10,000+ PSI (690+ bar)

Water Systems:

Residential water main: 40-80 PSI (2.8-5.5 bar)
Residential minimum: 20 PSI (1.4 bar)
Fire hydrant: 50-70 PSI (3.4-4.8 bar)
High-rise buildings: 60-100 PSI (4.1-6.9 bar)

Scuba Diving

Dive Tank Pressure:

Aluminum 80 (full): 3,000 PSI (207 bar)
Steel tanks (full): 3,300-3,500 PSI (228-241 bar)
Low pressure warning: 500 PSI (34 bar)

Underwater Pressure (per depth):

Surface (0 ft): 1 atm (14.7 PSI)
33 ft (10 m): 2 atm (29.4 PSI)
66 ft (20 m): 3 atm (44.1 PSI)
99 ft (30 m): 4 atm (58.8 PSI)

Common Conversion Mistakes

Mistake 1: Confusing Absolute vs Gauge Pressure

Error: Not distinguishing between PSI and PSIG (gauge pressure) Correction:

PSIG (gauge) = pressure relative to atmospheric (0 PSIG = 14.7 PSIA)
PSIA (absolute) = pressure relative to perfect vacuum
Most tire gauges, air compressors show PSIG

Mistake 2: Tire Pressure Units

Error: "My tire says 240, that's 240 PSI!" Correction: 240 kPa, not PSI! 240 kPa = 35 PSI. European cars show kPa on tire placard.

Mistake 3: Weather Pressure Confusion

Error: "Barometric pressure is 30" Correction: Specify units! Could be 30 inHg (high pressure) or 30 mbar (impossible). Standard is ~30 inHg or ~1013 mbar.

Mistake 4: Blood Pressure Units

Error: Converting mmHg to PSI for blood pressure Correction: Blood pressure is always measured in mmHg. Don't convert—120/80 mmHg is the universal standard.

Mistake 5: Bar vs mbar

Error: Using bar instead of mbar for weather Correction:

Weather: millibar (mbar) or hectopascal (hPa) - same value
Standard atmosphere = 1.013 bar = 1013 mbar

Mistake 6: Altitude Pressure Adjustments

Error: Using sea-level pressure formulas at altitude Correction: Atmospheric pressure drops ~1 inHg per 1,000 ft elevation. Adjust conversions and specifications accordingly.