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The Pressure Converter (General) is a comprehensive tool for converting between all major units of pressure. Whether you need to convert Pascals to PSI, bars to atmospheres, torr to millibars, or any other combination, this converter delivers instant, accurate results for 9 commonly used pressure units.
Pressure is a fundamental physical quantity defined as force per unit area. The SI unit of pressure is the Pascal (Pa), named after Blaise Pascal, equal to one Newton per square meter (N/m²). However, numerous other pressure units remain in widespread use across different industries: PSI (pounds per square inch) dominates in the United States for tire pressure, hydraulic systems, and industrial applications; bars and millibars are standard in meteorology and European engineering; atmospheres are used in chemistry and diving; and torr (equivalent to mmHg) is essential in vacuum science and medicine.
Understanding pressure conversions is critical for professionals working across international boundaries. An engineer designing a pneumatic system may receive specifications in bars but need to order components rated in PSI. A meteorologist may read pressure data in millibars but report it in inches of mercury for American audiences. Our converter handles all these scenarios with precise conversion factors derived from the definitions of each unit relative to the Pascal.
This tool supports conversions across 9 units spanning a vast range of magnitudes: from Pascals (ideal for small pressures in acoustics and low-pressure systems) through kilopascals and bars (standard for industrial and automotive use) to megapascals (used in materials science and structural engineering for yield strengths and tensile stresses). Each conversion uses internationally standardized conversion factors to ensure accuracy to at least 6 significant digits.
The converter works by first converting the input value to Pascals (the SI base unit of pressure), then converting from Pascals to the target unit. This two-step process, known as a hub-and-spoke conversion, ensures accuracy across all 72 possible unit combinations (9 × 8).
Key conversion factors to Pascals: 1 kPa = 1,000 Pa, 1 MPa = 1,000,000 Pa, 1 bar = 100,000 Pa (exact), 1 atm = 101,325 Pa (exact, by definition), 1 PSI ≈ 6,894.757 Pa, 1 torr ≈ 133.322 Pa, 1 inHg ≈ 3,386.389 Pa, 1 mbar = 100 Pa (exact).
Standard atmospheric pressure at sea level is 101,325 Pa = 101.325 kPa = 1.01325 bar = 1 atm = 14.6959 PSI = 760 torr = 29.9212 inHg = 1013.25 mbar. This reference point is fundamental across all pressure measurements. Tire pressures typically range from 30–35 PSI (207–241 kPa) for passenger cars. Blood pressure is measured in mmHg (torr), with normal systolic around 120 mmHg (16 kPa).
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1 atm = 14.696 PSI
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2.5 bar = 250 kPa
The Pascal (Pa) is the SI unit of pressure, defined as one Newton per square meter (N/m²). It is named after the French mathematician and physicist Blaise Pascal.
1 standard atmosphere (atm) equals exactly 14.6959 PSI. This is defined as the pressure exerted by Earth's atmosphere at sea level under standard conditions.
1 bar = 100,000 Pa while 1 atm = 101,325 Pa. A bar is slightly less than an atmosphere (1 atm ≈ 1.01325 bar). Bar is more common in European engineering; atmosphere is used in chemistry and diving.
Different pressure units evolved from different measurement traditions. PSI from imperial/US customary systems, Pascal from SI, bar from CGS/meteorology, torr from mercury manometer measurements, and atmosphere from Earth's natural air pressure.
1 torr ≈ 1 mmHg. They are nearly identical — torr is defined as exactly 1/760 of a standard atmosphere (133.322 Pa), while mmHg depends on mercury density and gravity. The difference is negligible for practical purposes.
In the US, tire pressure is measured in PSI. In most other countries, it is measured in bar or kPa. Typical car tires require 30–35 PSI (2.1–2.4 bar or 207–241 kPa).
A kilopascal is 1,000 Pascals. Standard atmospheric pressure is 101.325 kPa. It is commonly used in meteorology, engineering, and for tire pressures outside the US.
Absolute pressure = gauge pressure + atmospheric pressure. Gauge pressure reads zero at atmospheric pressure, while absolute pressure reads zero in a perfect vacuum.
Megapascals (MPa) are used in materials science and structural engineering to express tensile strength, yield strength, and Young's modulus. For example, structural steel has a yield strength of about 250 MPa.
All conversions use internationally standardized conversion factors. Results are accurate to the full precision of floating-point arithmetic (about 15–16 significant digits).
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