Pressure Converter

Convert between pascals, kilopascals, bar, atmospheres, PSI, mmHg, inHg, and torr instantly.

Value

From

Common Pressure Conversions

From	To	Result
1 atm	PSI	14.6959 psi
1 atm	kPa	101.325 kPa
1 atm	bar	1.01325 bar
1 bar	PSI	14.5038 psi
1 bar	kPa	100 kPa
1 PSI	kPa	6.89476 kPa
1 atm	mmHg	760 mmHg
1 MPa	bar	10 bar

Frequently Asked Questions

Standard atmospheric pressure (1 atm) is defined as 101,325 Pa = 101.325 kPa = 1.01325 bar = 14.6959 psi = 760 mmHg. This is the average air pressure at sea level. Actual atmospheric pressure varies with altitude, temperature, and weather conditions.

PSI (pounds per square inch) is used in the United States for tire pressure (typically 30–35 psi), blood pressure measurement, hydraulic systems, industrial equipment, and gas cylinders. Most of the world uses kPa or bar for these applications instead.

The Pascal (Pa) is the SI unit of pressure, defined as one newton per square meter (N/m²). It is named after mathematician Blaise Pascal. One pascal is a very small pressure — standard atmospheric pressure is about 101,325 Pa. Kilopascals (kPa) are more practical for most applications.

One bar = 100,000 Pa, while 1 atm = 101,325 Pa. 1 bar ≈ 0.9869 atm — very close but not equal. The bar is commonly used in meteorology, industrial processes, and European tire gauges. At standard conditions, a tire inflated to "1.5 bar gauge" has 2.5 bar absolute pressure (adding 1 atm ambient).

All three measure pressure but use different scales: 1 psi = 6,894.76 Pa = 0.0689 bar. The Pascal (Pa) is the SI unit; 1 Pa = 1 N/m². The bar is used in industry and meteorology (1 bar = 100,000 Pa ≈ 14.5 psi). PSI (pounds per square inch) is used primarily in the US for tires, air compressors, and hydraulic systems.

Standard atmospheric pressure at sea level is exactly 101,325 Pa = 1.01325 bar = 14.696 psi = 760 mmHg = 1 atm. Actual pressure varies with weather — high pressure (anticyclone) is typically 1020–1030 hPa, while a powerful hurricane can drop below 900 hPa at its center.

Blood pressure is measured in millimeters of mercury (mmHg) because early sphygmomanometers used mercury manometers. The unit persists due to medical convention. Normal blood pressure is about 120/80 mmHg (systolic/diastolic) = 16.0/10.7 kPa. In some countries, kPa is used instead, though mmHg remains the global medical standard.

Recommended tire pressure for most passenger cars is 30–35 psi (2.07–2.41 bar or 207–241 kPa). This is gauge pressure — pressure above atmospheric. The correct value is printed on a sticker inside the driver's door. Under-inflation increases rolling resistance and heat buildup; over-inflation reduces traction and ride comfort.

Meteorologists use hectopascals (hPa), which are numerically identical to millibars (mbar), to measure atmospheric pressure. Falling pressure typically indicates approaching storms; rising pressure signals clearing weather. A barometer reading below 1000 hPa suggests unsettled weather, while above 1020 hPa indicates fair conditions.

Multiply bar by 14.5038 to get psi. For a quick estimate, multiply by 14.5. For example, 2.5 bar × 14.5 ≈ 36.25 psi (exact: 36.26 psi). To convert psi to bar, divide by 14.5038 or multiply by 0.0689. European tire gauges show bar; US gauges show psi.

About This Pressure Converter

This free pressure converter converts between pascals, kilopascals, megapascals, bar, millibar, PSI, atmospheres, torr, and mmHg. Enter a value in any unit for instant results.

When to use this converter

Converting tyre pressure between PSI and bar
Reading weather pressure in hPa, inHg, or mbar
Engineering and hydraulics pressure calculations

Standards & References

NIST — SI Units (pascal)

How It Works

Enter Pressure

Type the pressure value. All conversions use the pascal (Pa) as the SI base unit of pressure.

Select Units

Choose from metric, imperial, and scientific pressure units. Both absolute and gauge-referenced conversions are straightforward.

Read Result

Instant conversion with exact factor displayed. The reference table shows the most common pressure equivalents at a glance.

Common Use Cases

Tire Pressure

Convert tire pressure between PSI (US vehicles), kPa (international), and bar (European gauges) for vehicle maintenance and safety checks.

Medical & Blood Pressure

Convert blood pressure readings between mmHg (standard clinical units) and kPa or other units for international medical references.

Meteorology

Convert barometric pressure between hPa/mbar, inHg, and mmHg for weather forecasting and comparing international weather data.

Industrial Systems

Convert hydraulic and pneumatic system pressures between bar, PSI, and MPa for equipment specifications and international supplier comparisons.

Diving & Altitude

Convert water and atmospheric pressures for scuba diving depth calculations, altitude sickness thresholds, and aviation applications.

Physics & Chemistry

Convert pressures for gas law calculations, reaction conditions, and thermodynamic analysis in chemistry and physics coursework.

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