Pressure Converter

How to Use the Pressure Converter

The Pressure Converter transforms measurements between all standard pressure units. From checking tire pressure in PSI versus bar, to interpreting weather reports in millibars, to medical blood pressure readings in mmHg, this tool covers every pressure conversion scenario.

Supported Units

Convert between pascals (Pa), kilopascals (kPa), megapascals (MPa), bar, millibar (mbar), atmosphere (atm), pounds per square inch (PSI), millimeters of mercury (mmHg), torr, and inches of mercury (inHg). Each unit serves specific industries and applications.

Key Conversion Factors

1 atm = 101,325 Pa = 101.325 kPa = 1.01325 bar = 14.696 PSI = 760 mmHg = 760 torr = 29.921 inHg. 1 bar = 100,000 Pa = 14.504 PSI. 1 PSI = 6,894.76 Pa = 0.06895 bar = 51.715 mmHg.

Common Applications

Tire Pressure: US tire pressure is in PSI (typically 30-35 PSI for cars). European standards use bar (2.0-2.4 bar). 32 PSI ≈ 2.21 bar.

Weather: Barometric pressure is reported in millibars (mbar), hectopascals (hPa, same as mbar), or inches of mercury (inHg). Standard atmospheric pressure is 1013.25 mbar or 29.92 inHg.

Medical: Blood pressure is measured in mmHg. Normal is around 120/80 mmHg. This unit persists from the mercury sphygmomanometers historically used.

Understanding Pressure

Pressure is force per unit area. One pascal equals one newton per square meter. Atmospheric pressure at sea level is the weight of the air column above you. At higher elevations, atmospheric pressure decreases. Weather systems bring pressure changes: high pressure generally means clear skies, low pressure often brings clouds and precipitation.

Frequently Asked Questions

Q: What tire pressure should I use?

A: Check the sticker inside your car door jamb or your owner manual for the recommended PSI. It is typically 30-35 PSI for passenger cars. Do not use the maximum pressure printed on the tire sidewall. Check pressure when tires are cold for accurate readings.

Q: Why is blood pressure measured in mmHg?

A: The unit originates from mercury manometers used in early blood pressure devices. Despite modern digital devices, the medical community retained mmHg as the standard unit for blood pressure readings worldwide for consistency with decades of clinical data and guidelines.

Q: What is the difference between gauge pressure and absolute pressure?

A: Absolute pressure is measured relative to a perfect vacuum (0 reference). Gauge pressure is measured relative to atmospheric pressure. A tire at 32 PSI gauge has an absolute pressure of about 46.7 PSI (32 + 14.7 atm). Most everyday measurements use gauge pressure.