zztool What is Pressure?
Pressure is the force applied perpendicular to the surface of an object per unit area. In the International System of Units (SI), pressure is measured in Pascal (Pa), which equals one Newton per square meter. Pressure is widely used in engineering, meteorology, medicine, and aviation, with different industries preferring different units.
Common Conversions
Use Cases
Tire pressure monitoring, commonly uses psi or bar
Hydraulic systems, pneumatic equipment
Atmospheric pressure, commonly uses hPa or mbar
Blood pressure measurement, uses mmHg
Cabin pressure, altimeter calibration
Vacuum systems, laboratory measurements
FAQ
Why is tire pressure in psi but blood pressure in mmHg?
This is due to historical and industry conventions. The US automotive industry uses psi, while medicine continues using mmHg from traditional mercury sphygmomanometers. Different units have become standards in their respective fields.
What is the difference between bar and atm?
Bar is a metric unit where 1 bar = 100,000 Pa; atm is standard atmosphere where 1 atm = 101,325 Pa. They are very close, but bar is easier for calculations while atm has more physical significance.
What is absolute pressure vs gauge pressure?
Absolute pressure is measured relative to vacuum, gauge pressure is relative to atmospheric pressure. Gauge = Absolute - Atmospheric. Tire pressure is typically gauge pressure.
How to choose the right pressure unit?
Choose based on application: engineering uses bar/MPa; US uses psi; meteorology uses hPa/mbar; medicine uses mmHg; scientific research uses Pa.
Many units supported.
Accurate pressure conversion.
Great for engineering!