Pressure Converter

Convert between pascals, bar, psi, atmospheres, mmHg, and other pressure units instantly, normalized to pascals for accurate results in engineering, meteorology, and medicine.

How to Use

  1. Enter the pressure value

    Type the pressure value you want to convert.

  2. Select the units

    Choose the source unit (e.g., psi) and the target unit (e.g., bar).

  3. View the result

    Click Convert to see the converted pressure value.

What are pressure units?

Pressure is the amount of force applied per unit area, and in the International System of Units (SI) it is expressed in pascals (Pa). One pascal is the pressure produced when a force of one newton acts on one square meter. Because that value is far too small for everyday use, different fields have adopted their own units.

Different units for different fields

  • Meteorology: Atmospheric pressure in weather forecasts is shown in hectopascals (hPa), with one atmosphere being about 1,013 hPa.
  • Engineering and industry: Boilers and hydraulic equipment use bar and megapascals (MPa).
  • Automotive: Tire pressure is given in psi in the US and in bar in Europe.
  • Medicine: Blood pressure is measured in millimeters of mercury (mmHg).

This converter first converts every unit to the SI base of pascals and then recalculates into the target unit, so you can accurately compare pressure values from completely different fields.

Calculation Formula

All pressure units are standardized to the base unit, the pascal (Pa), before being converted.

result = input value × (Pa factor of the source unit) ÷ (Pa factor of the target unit)

Example) To convert a tire pressure of 2.4 bar to psi, 2.4 × 100,000 = 240,000 Pa, then dividing by 6,894.76 gives 240,000 ÷ 6,894.76 ≈ 34.81 psi.

  • Key conversion factors (Pa per unit): atm 101,325 · bar 100,000 · psi 6,894.76 · mmHg/Torr 133.322 · inHg 3,386.39 · hPa 100 · kPa 1,000 · MPa 1,000,000

Frequently Asked Questions

How many pascals (Pa) are in one atmosphere (atm)?
One standard atmosphere (atm) is exactly 101,325 pascals (Pa). That corresponds to about 1,013.25 hPa (hectopascals), 1.01325 bar, or 760 mmHg, and is defined as the average atmospheric pressure at sea level.
What is psi?
Psi (pounds per square inch) is a pressure unit expressing pounds of force per square inch, used mainly in the US for things like tire pressure. One psi is about 6,894.76 Pa, and one bar is about 14.5 psi.
What is the mmHg used for blood pressure?
mmHg (millimeters of mercury) expresses pressure as the height of a column of mercury. One mmHg is about 133.322 Pa, and it is the medical standard for measuring blood pressure. Normal blood pressure is typically around 120 mmHg systolic / 80 mmHg diastolic.
For car tire pressure, should I read psi or bar?
Both express the same pressure in different units. One bar is about 14.5038 psi, and the recommended pressure for a typical passenger car is around 32-35 psi (about 2.2-2.4 bar). European manuals usually list bar while US ones use psi, so convert to whichever unit matches your vehicle.
Are Torr and mmHg the same unit?
They are nearly identical. One Torr is defined as 1/760 of an atmosphere while one mmHg is the height of a 1 mm column of mercury, but the difference between the two is only about 0.000015%, so in practice they are treated as the same value (about 133.322 Pa). Torr is used in vacuum engineering and mmHg in medicine.
What is the hPa (hectopascal) used in weather forecasts?
A hectopascal (hPa) means 100 pascals and has exactly the same value as the formerly used millibar (mb). 1 hPa = 1 mb, and standard atmospheric pressure is 1,013.25 hPa. The lower a typhoon's central pressure, such as 950 hPa, the lower the pressure and the stronger the storm.
In which fields is MPa used?
The megapascal (MPa) is one million pascals and is used in industrial fields dealing with high pressure. One MPa equals about 10 bar or about 145 psi, and it is the standard unit for high-pressure environments such as concrete strength, hydraulic equipment, and hydrogen refueling stations (about 70 MPa).
How do absolute pressure and gauge pressure differ?
Absolute pressure is the actual pressure measured from a perfect vacuum (0 Pa), while gauge pressure treats atmospheric pressure (about 101,325 Pa) as zero and shows how much higher the pressure is above it. A gauge-measured value like tire pressure must have atmospheric pressure added to become absolute pressure. This converter only performs unit conversion, so you should compare values referenced to the same baseline.
2026 international standards

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