Conversion Runs locally Ready to use Built-in examples No tracking

Pressure Converter

Convert between eight pressure units: Pa, kPa, MPa, bar, atm, mmHg, mH2O and psi. Car tyre pressure of 2.2–2.5 bar is roughly 220–250 kPa or 32–36 psi, and standard atmospheric pressure is 101.325 kPa = 1 atm = 760 mmHg — useful for tyre gauges, blood-pressure monitors and engineering specs.

A tyre gauge reads bar or psi, a blood-pressure monitor reads mmHg, engineering drawings specify MPa — every trade has its own pressure habit. This tool converts between Pa, kPa, MPa, bar, atm, mmHg, mH2O and psi; the anchors are standard atmosphere 101.325 kPa = 1 atm = 1.01325 bar = 760 mmHg ≈ 14.7 psi.

Useful references: household tyre pressure of 2.2–2.5 bar is roughly 220–250 kPa or 32–36 psi, and reading the gauge in the wrong unit puts the figure out by a factor of 14; a blood pressure of 120 mmHg is about 16 kPa; and every 10 metres of depth under water adds roughly one atmosphere. Engineering work uses Pa or MPa, while everyday checks use bar and psi.

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How to use

  1. Enter the pressure and pick its unit.
  2. Read the equivalents in the other units.
  3. Check the unit on the gauge before comparing figures.
  4. Use bar or psi for tyre checks, and Pa or MPa for calculations.

How it works

Basic usage

Enter a value, pick the source and target units, and it converts live; the swap button reverses direction in one click.

Tire pressure (bar / psi)

Tire pressure: Chinese gauges usually use bar, US-spec cars label psi. 2.5 bar x 14.5038 is about 36.26 psi.

Blood pressure (mmHg / kPa)

Blood pressure: mmHg is the medical convention, 120 mmHg is about 16 kPa; engineering uses MPa and bar (1 MPa = 10 bar).

Code example

JavaScript kPa as the hub 

const KPA = { Pa: 0.001, kPa: 1, MPa: 1000, bar: 100,
              atm: 101.325, mmHg: 0.133322, mH2O: 9.80665,
              psi: 6.894757 };

const convert = (v, from, to) => v * KPA[from] / KPA[to];

convert(2.5, "bar", "psi");    // 36.26 (tyre pressure)
convert(760, "mmHg", "kPa");   // 101.32 (standard atmosphere)

Python The same coefficients in Python 

KPA = {"Pa": 0.001, "kPa": 1, "MPa": 1000, "bar": 100,
       "atm": 101.325, "mmHg": 0.133322, "psi": 6.894757}

convert = lambda v, f, t: v * KPA[f] / KPA[t]

convert(120, "mmHg", "kPa")   # 16.0 (systolic blood pressure)
convert(35, "psi", "bar")     # 2.41

FAQ

What is a tire pressure of 2.5 in psi?

2.5 bar is about 36.26 psi (1 bar = 14.5038 psi). US vehicles label psi on the door frame; Chinese gauges mostly use bar or kPa.

How do mmHg and kPa convert?

1 mmHg = 0.133322 kPa, and 760 mmHg = 101.325 kPa (standard atmosphere). A monitor reading of 120/80 mmHg is about 16/10.7 kPa.

Are bar and atm the same?

Not the same but close: 1 bar = 100,000 Pa (by definition), 1 atm = 101,325 Pa (standard atmosphere). 1 atm is about 1.01325 bar — treat as 1:1 for rough everyday use, convert precisely for accuracy.

How is the pascal defined?

1 pascal (Pa) = 1 newton per square meter, the SI pressure unit; 1 kPa = 1000 Pa, 1 MPa = 1,000,000 Pa. Everyday tire pressure and blood pressure numbers are moderate, so kPa or bar is common; industrial piping uses MPa.

How do blood-pressure mmHg convert to kPa?

1 mmHg is about 0.1333 kPa, 1 kPa about 7.5 mmHg. For example 120/80 mmHg is about 16.0/10.7 kPa. China uses mmHg; some countries use kPa — distinguish units when seeing a doctor or using imported devices.

What does one standard atmosphere equal?

1 standard atmosphere (atm) = 101.325 kPa = 1.01325 bar = 760 mmHg, about 14.696 psi. It's a common pressure reference, so "two atmospheres" is about 202.65 kPa.

Should car tire pressure use bar or psi?

Either works; China often says bar (or kg/cm2), Europe and America use psi. Passenger-car pressure is commonly 2.2-2.5 bar, about 32-36 psi. Follow the door-frame label or manual rather than inflating by feel.