Pressure Unit Conversion

Engineering Mechanics & Pressure Metrology

In mechanical engineering, aviation, and fluid dynamics, Pressure represents force acting perpendicularly over a cross-sectional unit area. Unit conversions require converting between coherent SI units and non-SI imperial and gravitational scales.

Primary Conversion Factors (Base SI: Pascals)

• 1 Pascal (Pa) = 1.00000 N/m^2

• 1 Kilopascal (kPa) = 1,000 Pa = 0.01 bar = 0.145038 PSI

• 1 Megapascal (MPa) = 1,000,000 Pa = 10 bar = 145.038 PSI

• 1 Bar = 100,000 Pa = 100 kPa = 14.50377 PSI = 1,000 mbar

• 1 Millibar / Hectopascal = 100 Pa = 0.001 bar

• 1 Pound per Square Inch (PSI) = 6,894.757 Pa = 6.89476 kPa = 0.068948 bar

• 1 Standard Atmosphere (atm) = 101,325 Pa = 1.01325 bar = 14.69595 PSI

• 1 Torr (mmHg) = 133.3224 Pa = 0.019337 PSI

Application Specific Pressure Units

• Automotive Tires: Typically calibrated in PSI (USA) or Bar (Europe, 1 bar ≈ 14.5 psi).

• Meteorology: Weather charts express atmospheric barometric pressure in Hectopascals (hPa) or Millibars (mbar), which are numerically identical.

• High-Pressure Hydraulics: Industrial oil hydraulic circuits are rated in Megapascals (MPa).

How to Use This Calculator

Enter your Pressure Magnitude (e.g. 32.0), Source Unit (From) — choose from Pounds per Square Inch (PSI / psi), Bar (bar), Millibar / Hectopascal (mbar / hPa), and Target Unit (To) — choose from Bar (bar), Pounds per Square Inch (PSI / psi), Millibar / Hectopascal (mbar / hPa). Results update instantly as you type — adjust any value to compare scenarios.

The Formula

Conversion factors (to SI base unit or reference unit):

pascals: 1.0

kilopascals: 1000.0

megapascals: 1000000.0

bar: 100000.0

millibar_hpa: 100.0

atmospheres: 101325.0

psi: 6894.757293168

torr_mmhg: 133.322387415

pounds_per_sq_ft: 47.88025898

Worked Example

Converting a recommended car tire pressure of 32.0 PSI to European metric units: Yields 2.2063 bar.

Understanding Your Result

Unit conversions are exact by definition within a given measurement system (e.g., 1 km = exactly 1,000 m). Cross-system conversions (metric to imperial) use defined exchange factors: 1 inch = exactly 2.54 cm; 1 pound = 0.45359237 kg. Round your converted result to match the precision of your original measurement — expressing more decimal places than your input justifies implies false accuracy. For regulatory, legal, or safety-critical applications, verify which measurement system is required by the applicable standard.