Pound per Square Inch to Millimeter of Mercury Converter

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 →

How do I convert PSI to bar?

Formula: Bar = PSI × 0.0689476 (or divide PSI by 14.5)

Examples:

• 10 PSI = 0.69 bar
• 30 PSI = 2.07 bar
• 50 PSI = 3.45 bar
• 100 PSI = 6.89 bar

Quick mental math: Divide PSI by 14.5 or 15

• 30 PSI ÷ 15 ≈ 2 bar (actual: 2.07)

Use our PSI to Bar converter →

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:

1. Check driver's door jamb sticker
2. Consult owner's manual
3. 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 →