Pressure Units
Convert between PSI, bar, pascal, atmosphere, and more pressure units.
Automotive & Weather
Perfect for tire pressure, weather forecasting, and industrial applications.
Scientific Precision
Accurate conversions for engineering, diving, and scientific research.
Understanding Pressure Conversion
Pressure measures force per unit area, expressed in various units across different fields. The SI unit is the pascal (Pa), defined as one newton per square meter. Common units include bar, PSI (pounds per square inch), atmosphere (atm), and millimeters of mercury (mmHg). One bar equals 100,000 pascals, while standard atmospheric pressure is 101,325 Pa or 1 atm.
Tire pressure is typically measured in PSI (US) or bar (Europe): 30 PSI equals approximately 2.07 bar. Weather reports use hectopascals (hPa) or mill ibars (mb), where 1 hPa = 1 mb = 100 Pa. Understanding pressure conversions is essential for automotive specifications, weather forecasting, diving calculations, and industrial applications.
Common Usage Examples
- Automotive: Tire pressure specifications (PSI vs bar)
- Weather: Atmospheric pressure in meteorology (hPa, mb)
- Diving: Underwater pressure calculations in atmospheres
- Engineering: Hydraulic system pressure ratings
- Aviation: Cabin pressure and altitude measurements
- Industrial: Compressed air and gas pressure systems
Frequently Asked Questions
How do I convert PSI to bar?
Divide PSI by 14.504. For example, 30 PSI ÷ 14.504 ≈ 2.07 bar. This is useful for tire pressure conversions between US and European specifications.
What is atmospheric pressure?
Standard atmospheric pressure at sea level is 1 atmosphere (atm), equal to 101,325 pascals, 1.01325 bar, or 14.7 PSI. It decreases with altitude.
Why is tire pressure measured in PSI or bar?
PSI (pounds per square inch) is traditional in the US, while bar is standard in Europe. Both are convenient scales for typical tire pressures (30-35 PSI or 2-2.4 bar).
What's the difference between gauge and absolute pressure?
Gauge pressure measures relative to atmospheric pressure, while absolute pressure includes atmospheric pressure. A tire gauge showing 30 PSI is measuring gauge pressure; absolute would be ~44.7 PSI.