Pressure Unit Converter: Convert psi to bar, kPa to psi, bar to psi, atm to psi, and more

Choose the relevant units, and then put the value of the pressure you want to convert in the input field and see the live conversions.

Pressure

Pressure is defined as force per unit area. The SI units of pressure are N/m² or Pascals (Pa). Pressure can also be expressed using units of pounds per square inch (psi) that is in American engineering system.

Pressure Measurement

There are common terms you will likely encounter in pressure measurements, explained as follows:

Total vacuum – this is zero pressure or lack of pressure, as would experience in outer space.

Vacuum – pressure measurement made between total vacuum and normal atmospheric pressure (14.7 psi).

Atmospheric pressure – this is the pressure on the earth’s surface due to the weight of the gases in the earth’s atmosphere, and is normally expressed at sea level as 14.7 psi or 101.36 kPa. But it is dependent on atmospheric conditions. The pressure decreases above sea level and at an elevation of 5000 feet drops to about 12.2 psi (84.122 kPa).

Absolute pressure – this is the pressure measured with respect to a vacuum and is expressed in pounds per square inch absolute (psi).

Gauge pressure – this is the pressure measured with respect to atmospheric pressure and is normally expressed in pounds per square inch gauge (psig).

Differential pressure – is the pressure measured with respect to another pressure and is expressed as the difference between the two values. This can represent two points in a pressure or flow system.

A number of measurement units re used in pressure measurements, examples include:

• Pounds per square inch (psi), common in US engineering, automotive and hydraulics (1 psi = 6894.76 Pa).
• Atmosphere (atm), useful for standard atmospheric comparisons (1 atm = 101,325 Pa).
• Pascal (N/m²) – SI unit or kilopascal (1000 Pa)
• Bar (1.013 atm) = 100 kPa
• mmHg (millimeter of mercury), typical applications in medical and vacuum systems.
• inH₂O (Inch water column) – you will find it pressure HVAC and gas distribution.
• Torr = 1 mm Mercury

Quick pressure unit conversion

• 1 Pa = 1 N/m²
• 1 kPa = 1000 Pa
• 1 bar = 100,000 Pa
• 1 atm = 101,325 Pa
• 1 psi = 6,894.76 Pa
• 1 mmHg = 133.322 Pa
• 1 inH₂O (4°C) = 249.089 Pa

Use multiplication/division by those factors to convert between the units.

The tables below show how to convert between the various pressure measurement units.

Pressure Conversions Tables

Table 1.0: Pressure Conversion Chart

Convert From	To	Multiply By
pascals (pa)	Pounds per square inch (psi)	0.000145038
Pounds per square inch (psi)	pascals (pa)	6894.76
kilopascals (kPa)	pounds per square inch (psi)	0.145038
bar	pounds per square inch (psi)	14.5038
megapascals (MPa)	pounds per square inch (psi)	145.038

Table 1.1: Pressure Conversions (Conversion Factors Between Units)

	Pascal (Pa)	Bar (bar)	Millibar (mbar)	Standard atmosphere (atm)	Kilogram force per square                                 cm (kgf/cm2)	Pounds force per square inch (lbf/in2)	Torr	Millimeter of water (mmH2O)	Millimeter of mercury (mmHg)	Inch of Water (inH2O)	Inch of mercury (inHg)
Pa	1	10-5	10-2	9.8693 x 10-6	1.01972 x 10-5	1.45038 x 10-4	7.50062 x 10-3	1.01972 x 10-1	7.50062 x 10-3	4.0143 x 10-3	2.95300 x 10-4
bar	105	1	103	9.86923 x 10-1	1.01972	14.5038	7.50062 x 10-2	1.01972 x 10-2	7.50062 x 102	4.0163 x 10-8	29.5300
mbar	102	10-3	1	9.86923 x 10-4	1.01972 x 10-3	1.45038 x 10-2	7.50062 x 10-1	1.01972 x 10	7.50062x 10-1	4.01462 x 10-1	2.95300 x 10-2
atm	1.01325 x 105	1.01325	1.01325 x 103	1	1.03323	1.46959 x 10	7.60000 x 102	1.03323x 105	760	4.06783 x 102	29.9213
kgf/cm2	98066.5	0.980665	980665	0.967841	1	14.233	735.559 x 102	104	7.35559 x 102	3.93700 x 102	28.9590
lbf/in2	6894.76	0.0689476	68.9476	6.80460 x 10-2	7.03070 x 10-2	1	51.7149	7.03069x 102	51.7149	27.6798	2.03602
torr	133.322	1.33322 x 10-3	1.33322	1.31579 x 10-3	1.35951 x 10-3	1.93368 x 10-2	1	13.5951	1	53.5240	3.93701 x 10-2
mmH2O	9.80665	9.80665 x 10-5	9.80665 x 102	9.67841 x 10-5	10-4	1.42233 x 10-3	7.35559 x 10-2	1	7.35559 x 10-2	3.9301 x 10-2	2.89590 x 10-3
mmHg	133.322	1.33322 x 10-3	1.33322	1.31579 x 10-3	1.35951 x 10-3	1.93368 x 10-2	1	13.5951	1	53.5240	3.9301x 10-2
inH2O	249.089	2.49089 x 10-3	2.49089	2.45831 x 10-3	2.54 x 10-3	3.61272 x 10-2	1.86832	25.4	1.86832	1	7.35559 x 10-2
inHg	33.8639	3.38639 x 10-2	33.8639	3.34211 x 10-2	3.453 x 10-2	0.491154	25.4000	3.45316x 10-2	25.4000	13.5951	1

For example, using the above table, to convert pressure from bar to mmHg, you will multiply by 7.50062 x 10² (Move across the bar row, till you come to the column of mmHg to locate this factor)

Assume I have a pressure of 2 bars, to convert to pressure in mmHg: 2 x 7.50062 x 10² ≈ 1.500.13 mmHg

Why Pressure Measurement Is Important

Pressure measurement is important because of several reasons, which include:

• Safety – detecting overpressure or vacuum prevents equipment failure, explosions, leaks, and protects personnel working on boilers, gas lines, and pressure vessels.
• Process control – pressure is a primary control variable in many chemical, oil and gas, HVAC and pneumatic systems; accurate pressure measurement ensures product quality and process efficiency.
• Flow and level calculations – many flowmeters and level sensors i.e. differential pressure sensors, rely on pressure differences to compute flow rates and liquid levels.
• Performance monitoring – turbines, pumps, compressors, etc. use pressure readings to assess performance, diagnose faults, and schedule maintenance.
• Medical applications – blood pressure, ventilators, and anesthesia systems require precise pressure measurement for diagnosis and patient safety.
• Environmental monitoring – atmospheric and underwater pressure data are essential for weather forecasting, climate studies, and oceanography.
• Lastly for calibration and standards, pressure standards and metrology maintain traceability across industries.

Practical Tips for Consideration in Pressure Measurement

When performing pressure measurement, you may consider the following practical tips:

• Use absolute pressure when working with sealed systems or thermodynamic calculations; use gauge pressure for equipment operating above or below ambient temperature.
• For small differentials select sensitive units (Pa, mmH₂O) and for large industrial pressures choose bar or psi.
• Ensure the instruments are specified for the correct pressure range and calibrated traceably.
• Compensate for temperature and altitude when high accuracy is required.

Also read:

• How to Connect a DP (Differential Pressure) Flow Sensor to a DP Transmitter
• Features & Configuration of a Smart Pressure Transmitter
• Standard Pipe Sizes
• Photoelectric Pressure Transducer Operation