MulticalcPressure Unit Converter
Convert between pressure units instantlyEnter a pressure value to see conversions.
Pressure Conversion Guide
Understanding Pressure Units
Pressure is force applied perpendicular to the surface of an object per unit area. Different industries and regions use different pressure units.
Common Pressure Units:
- PSI: Pounds per Square Inch - Common in US (tires, hydraulics)
- Bar: Metric unit, approximately 1 atmosphere
- Pascal (Pa): SI unit, 1 Pa = 1 N/m²
- kPa/MPa: Kilopascal/Megapascal - Larger Pascal units
- Atmosphere (atm): Standard atmospheric pressure at sea level
- mmHg/inHg: Mercury column height - Used in meteorology
- Torr: Approximately equal to mmHg
Quick Reference:
- 1 atm = 14.7 PSI = 1.01325 bar = 101,325 Pa
- 1 bar = 100,000 Pa = 100 kPa = 14.5 PSI
- 1 PSI = 6,894.76 Pa ≈ 0.0689 bar
- 1 mmHg = 1 torr ≈ 133.322 Pa
Common Applications
- Automotive: Tire pressure (PSI, bar, kPa)
- HVAC: Refrigerant pressure (PSI, bar)
- Medical: Blood pressure (mmHg)
- Weather: Atmospheric pressure (inHg, mbar)
- Industrial: Hydraulic systems (bar, MPa)
Pro Tips
-
Tire
Pressure
Car tires typically run at 30-35 PSI (2.0-2.4 bar). Check when cold for accuracy. -
Altitude Effect
Atmospheric pressure decreases with altitude. Sea level = 1 atm, 10,000 ft ≈ 0.69 atm. -
Gauge vs Absolute
Gauge pressure is relative to atmospheric. Absolute includes atmospheric pressure.
Standard Atmosphere
At sea level:
- 1 atm
- 14.696 PSI
- 1.01325 bar
- 101,325 Pa
- 760 mmHg
- 29.92 inHg
Frequently Asked Questions
A: PSI (Pounds per Square Inch) is an imperial unit commonly used in the US, while bar is a metric unit used internationally. 1 bar ≈ 14.5 PSI. Bar is approximately equal to atmospheric pressure at sea level.
A: Gauge pressure is measured relative to atmospheric pressure (what most pressure gauges show). Absolute pressure includes atmospheric pressure. For example, 30 PSI gauge = 44.7 PSI absolute (30 + 14.7 atm).
A: Historically, blood pressure was measured using mercury manometers, where pressure was indicated by the height of a mercury column in millimeters. The unit persists today even though digital devices are common. Normal blood pressure is around 120/80 mmHg.
A: Check the sticker on your driver's door jamb or owner's manual. Typical passenger cars use 30-35 PSI (2.0-2.4 bar). Always check tire pressure when tires are cold for accurate readings.
A: Atmospheric pressure decreases with altitude. At sea level, it's 1 atm (14.7 PSI). At 5,000 feet, it drops to about 0.83 atm. At 10,000 feet, it's approximately 0.69 atm. This affects cooking, breathing, and engine performance.
A: A Pascal (Pa) is the SI unit of pressure, defined as 1 Newton per square meter. It's small because it's based on fundamental SI units. That's why kPa (kilopascal) and MPa (megapascal) are more commonly used in practice. 1 kPa = 1,000 Pa.
Disclaimer
Important Notice:
- This converter provides accurate conversions based on standard conversion factors. However, always verify critical measurements with calibrated instruments.
- Conversions are rounded to 6 decimal places for display. For scientific or precision applications, use appropriate significant figures.
- Gauge vs Absolute: This converter assumes you're converting between the same type (both gauge or both absolute). Mixing types requires adding/subtracting atmospheric pressure.
- Pressure measurements can be affected by temperature, altitude, and measurement method. Always account for environmental conditions in critical applications.
- For safety-critical applications (pressure vessels, medical equipment, aviation), always use calibrated instruments and follow industry standards.
- Tire pressure should be checked when tires are cold. Driving heats tires and increases pressure readings.
- This tool is for general reference. For professional, medical, or safety-critical applications, consult with qualified professionals and use certified equipment.
- Conversion factors are based on standard definitions. Some industries may use slightly different values for historical reasons.
- We are not responsible for any errors, equipment damage, injuries, or other consequences resulting from the use of this converter.
Always verify conversions for critical applications and use properly calibrated equipment.
Pressure Converter
Convert between 9 common pressure units instantly. Perfect for automotive, HVAC, medical, and industrial applications!
Supported Units
- ✓ PSI (Pounds per Square Inch)
- ✓ Bar
- ✓ Pascal (Pa)
- ✓ Kilopascal (kPa)
- ✓ Megapascal (MPa)
- ✓ Atmosphere (atm)
- ✓ mmHg (Millimeter of Mercury)
- ✓ inHg (Inch of Mercury)
- ✓ Torr
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Did You Know?
The deepest part of the ocean (Mariana Trench) has a pressure of about 16,000 PSI (1,100 bar) - over 1,000 times atmospheric pressure at sea level!