Pressure Converter

Pressure Unit Converter

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Pressure Unit Conversion Guide

Pressure is force applied per unit area, and it is measured in many different units across medicine, meteorology, engineering, and everyday applications like tyre inflation. Our free online pressure converter supports eight widely used units, generating a complete reference table for any value you enter.

Pascal — The SI Unit of Pressure

The pascal (Pa) is the SI unit of pressure, defined as one newton per square meter. It is named after the French mathematician and physicist Blaise Pascal. Because the pascal is very small, kilopascals (kPa = 1,000 Pa) and megapascals (MPa = 1,000,000 Pa) are more commonly used in practice. Standard atmospheric pressure at sea level is 101,325 Pa (101.325 kPa).

Bar — Industrial Pressure

The bar is widely used in industry, meteorology, and engineering. One bar = 100,000 Pa, which is very close to one standard atmosphere (1 atm = 1.01325 bar). Scuba diving cylinders are pressurised to 200–300 bar. Weather maps in Europe show atmospheric pressure in millibars (mbar, 1 mbar = 100 Pa = 1 hPa).

PSI — Tyres and US Industry

Pounds per square inch (PSI) is the standard pressure unit in the United States for tyre pressure, hydraulic systems, and piping. Car tyre pressure is typically 30–35 PSI. One PSI equals 6,894.76 Pa or approximately 0.0689 bar. High-pressure applications in the US oil and gas industry can reach tens of thousands of PSI.

mmHg and Torr — Medicine and Vacuum

Millimetres of mercury (mmHg) and Torr are historically derived from barometer measurements using mercury columns. They are essentially the same unit (1 Torr = 1/760 atm ≈ 1 mmHg). Both are used in medical blood pressure readings (e.g., 120/80 mmHg is normal blood pressure) and vacuum technology.

Atmosphere (atm) and inHg — Weather

The standard atmosphere (atm) is defined as 101,325 Pa and represents the average air pressure at sea level. Inches of mercury (inHg) is used in aviation altimetry and US weather reports for barometric pressure. Standard sea-level pressure is 29.92 inHg.

Frequently Asked Questions

What is normal blood pressure in mmHg?
Normal adult blood pressure is approximately 120 mmHg (systolic) over 80 mmHg (diastolic), written as 120/80 mmHg. High blood pressure (hypertension) is defined as consistently above 130/80 mmHg. The mmHg unit remains standard in medicine worldwide.
What PSI should car tyres be inflated to?
Most passenger cars recommend 30–35 PSI (about 207–241 kPa or 2.07–2.41 bar) for tyre inflation. The exact value is on the tyre placard inside the driver's door. Over- or under-inflated tyres reduce safety and fuel efficiency.
How many PSI is 1 bar?
One bar equals approximately 14.5038 PSI. Conversely, 1 PSI = 0.0689476 bar. Tyre pressure gauges in Europe show bar; gauges in the US show PSI — our converter lets you switch between them instantly.
What is the difference between absolute and gauge pressure?
Absolute pressure is measured relative to a perfect vacuum (0 Pa). Gauge pressure (often written PSIg or barg) is measured relative to atmospheric pressure. A tyre gauge reads gauge pressure: 35 PSIg means 35 PSI above atmosphere, which is about 49.7 PSI absolute. Our converter uses absolute pressure values.
What is standard atmospheric pressure?
Standard atmospheric pressure is 101,325 Pa = 101.325 kPa = 1.01325 bar = 14.696 PSI = 1 atm = 760 mmHg = 760 Torr = 29.92 inHg. It represents the average air pressure at sea level and is used as a reference in many scientific calculations.