psi – Pounds per Square Inch Pressure Unit

Pounds or pound force per square inch (psi, lb/in², pfsi or lbf/in²) is a widely used British and American unit of measure for pressure. 1 psi equals 6,894.76 pascals.

In the USA the PSI pressure unit is the primary unit of measure for pressure and almost all pressure instruments are specified and display in pounds per square inch.

The psi is still used extensively in the UK but the bar pressure unit has mostly replaced it as the primary pressure unit.

Use the conversion factors below to convert from PSI to other pressure units or vice versa. To convert a reading in PSI to another unit multiply it by the relevant pressure conversion factor. To convert a reading in any pressure unit to PSI divide it by the relevant pressure conversion factor. Alternatively convert from a psi pressure value into another unit using the psi conversion table or the pressure unit converter.

Find out how psi is derived from SI units and view the alternative descriptions for psi.

• 100 psi g digital pressure gauge for pneumatic pressures
• 50 psig range hydrocarbon gases pressure gauge with 1/2 NPT male fitting
• Immersible sewage level transmitter for pressures up to 5 psi
• 200 bar (3000 psi) High accuracy pressure gauge and calibration pump with 0.05% accuracy

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Conversion Factors

• 0.0689476 bar
• 1 psi
• 68.9476 mbar
• 6894.76 N/m²
• 6894.76 Pa
• 68.9476 hPa
• 6.89476 kPa
• 0.00689476 MPa
• 0.0703070 kg/cm²
• 703.070 mmH2O 4°C (39.2°F)
• 70.3070 cmH2O 4°C (39.2°F)
• 0.703070 mH2O 4°C (39.2°F)
• 27.6799 inH2O 4°C (39.2°F)
• 2.30666 ftH2O 4°C (39.2°F)
• 51.7149 mmHg 0°C (32°F)
• 5.17149 cmHg 0°C (32°F)
• 2.03602 inHg 0°C (32°F)
• 51.7149Torr
• 51714.9 mTorr
• 0.0680460 atm
• 0.0703070 at
• 68947.6 dyn/cm²
• 16 oz/in²
• 51714.9 µHg 0°C (32°F)
• 0.000446429 tsi (uk, long)
• 0.000500000 tsi (usa, short)
• 0.0720000 tsf (usa, short)
• 144.000 psf
• 70.3070 g/cm²

Please note that the conversion factors above are accurate to 6 significant figures.

• 15psig 0-10Vdc output pressure sensor for nitrogen filled antenna line leak testing use
• 15psig 0-5Vdc out air gasoline mixture pressure sensor for automotive supercharger booster testing
• Duplex steel 1500psig 0-5V output seawater pressure sensor for water treatment use
• 20,000 psi g digital pressure gauge with 4 to 20 mA output

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Derivation

The calculation below shows how the pressure unit pounds per Square inch (psi) is derived from SI Units.

Formula

• Pressure = Force / Area
• Force = Mass x Acceleration
• Acceleration = Distance / (Time x Time)

SI Units

• Mass: kilogram (kg)
• Length: metre (m)
• Time: second (s)
• Force: newton (N)
• Pressure: pascal (Pa)

Input Values

• 1 Pound = 0.45359237 kg
• 1 Inch = 0.0254 m
• 1 Square Inch = 0.0254 m x 0.0254 m = 0.00064516 m²
• Acceleration = Standard Gravity = 9.80665 m/s²

Calculation

• 1 Pound Force = 0.45359237 kg x 9.80665 m/s² = 4.448221615 N
• 1 psi Pressure = 4.448221615 N / 0.00064516 m² = 6894.757293 Pa

• Injection moulding machine 22000 psig 4-20mA output synthetic hydraulic oil pressure sensor
• 5000 psi WECO® 1502 pressure transmitter and loop indicator
• 6,000 psig ATEX/IECEx IS approved 4-20mA pressure sensor for oil pumping use
• 50,000 psi logger, indicator and sensor for hose burst testing

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Alternate Descriptions

These are the different versions used for identifying psi that you may find elsewhere.

• Pounds Per Square Inch
• Pound Per Square Inch
• Pounds Force Per Square Inch
• Pound Force Per Square Inch
• psi
• pfsi
• lb/in²
• lbf/in²
• lb/sq in
• lbf/sq in
• lb/in^2
• lbf/in^2
• lbs/in²
• lbsf/in²
• lbs/sq in
• lbsf/sq in
• lbs/in^2
• lbsf/in^2

• High psi accuracy tire pressure checking transducer
• 320 degF steam temperature, 100 psi pressure transmitter
• 150 psig RS485 Modbus RTU chilled water pressure sensor for supply and return monitoring
• 50000 psig 4-20mA mineral hydraulic oil pressure sensor for chemical processing use

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Conversion Tables

Select a look up table for converting a pressure reading in pounds per square inch to other measurement units.

• mbar, hPa, Bar, inHg, mH2O, inH2O and ftH2O
• bar  »  1 to 100,000 psi → 0.0689476 to 6,894.76 bar
• mbar  »  0.1 psi to 100.0 psi → 6.89476 to 6,894.76 mbar
• Pa  »  0.01 psi to 20.00 psi → 68.9476 to 137,895 Pa
• hPa  »  0.1 psi to 100.0 psi → 6.89476 to 6,894.76 hPa
• kPa  »  1 to 1,000 psi → 6.89476 to 6,894.76 kPa
• MPa  »  100 to 100,000 psi → 0.689476 to 689.476 MPa
• kg/cm²  »  1 to 100,000 psi  → 0.0703070 to 7,030.70 kg/cm²
• g/cm²  »  0.01 to 20.00 psi  → 0.703070 to 1,406.14 g/cm²
• N/m²  »  0.01 psi to 20.00 psi → 68.9476 to 137,895 N/m²
• N/mm²  »  100 to 100,000 psi → 0.689476 to 689.476 N/mm²
• dyn/cm²  »  0.01 to 20.00 psi  → 689.476 to 1,378,950 dyn/cm²
• psf  »  0.01 to 20.00 psi → 1.44 to 2,880.00 psf
• oz/in²  »  0.1 to 100.0 psi → 1.6 to 1,600.0 oz/in²
• mH₂O  »  1 to 1000 psi → 0.703070 to 703.070 mH₂O
• inH₂O  »  0.01 to 20.01 psi → 0.276799 to 553.598 inH₂O
• ftH₂O  »  1 to 1,000 psi → 2.30666 to 2,306.66 ftH₂O
• mmHg  »  0.01 to 20.00 psi → 0.517149 to 1,034.30 mmHg
• inHg  »  0.01 to 20.00 psi → 0.0203602 to 40.7204 mmHg
• Torr  »  0.01 to 20.00 psi → 0.517149 to 1,034.30 Torr

• Elevated freshwater tank level 30 psig range 0-5Vdc out pressure sensor
• 5 psi delta air pressure sensor with 0 to 10 volt output
• 15000 psi combined pressure gauge and logger with USB interface
• 5 psi dp 0-10V out air pressure sensor for automation flow rate testing use on a 15psi line

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Help

20,000 psi to bar

What would be bar conversion scale for 0-20,000 psi range?

20,000 psi = 1,378.95… bar

780 psi to kPa

How to convert 780 psi to kPa?

780 psi = 5377.91 kPa

1 psi to oz/in²

How many oz/in² are there in 1 psi?

There are 16 oz in 1 lb, so 1 psi = 16 oz/in²

The 0-2 psi conversion scale below shows the conversion values around 1 psi.

0-200 psi to bar

What is european bar equivalent values for a 0-200 psi range?

This graphic shows the equivalent bar values over the range 0 to 200 psi:

lbf/in² meaning

What is  meaning of lbf/in² and the relationship to bar?

“lbf/in²” is one of the many acronyms used for “Pounds Force per Square Inch” pressure units of which “psi” is the most commonly used.  The factor for converting lbf/in² into bar is 0.068948., e.g. 15 psi = 1.03422 bar.

psi to bar

What is the equation for psi to bar?

psi to bar = multiply by 0.0689476…

psi to bar

What is the equation for psi to kPa?

psi to kPa = multiply by 6.89476…

22.2 psi to ftH2O

How do I convert 22.2 psi to feet of water and what is it?

1 psi = 2.30666 feet of water, therefore 22.2 psi = 51.2 feet of water.

The pressure unit “Feet of Water” is the pressure that a 1 foot high column of water exerts under the influence of gravity.

e.g. A storage tank which contains water up to a level of 51.2 feet will push down on the bottom of the tank with a pressure of 22.2 psi.

Seawater depth into psi

What is the reading in psi at 5000 ft below the surface of the ocean?

It’s approximately 2,168 psi if you assume the specific gravity density of freshwater at 4 degC of 1.0, the actual pressure will vary by a few percent depending the seawater properties.  Seawater has a varying density due to variations in salinity, temperature and pressure at different depths and geo-locations.

USA and UK psi

Is the US measure of psi the same as the UK?

Yes a USA psi is the same amount as a UK psi.

• Adjustable recording time 300 psi water pressure data logger with 1/4″NPT fitting
• Elevated freshwater tank level 30 psig range 0-5Vdc out pressure sensor
• 500 psi g Hydraulic pressure transducer with 0 to 10 volts signal output
• 15psig 0-10Vdc output pressure sensor for nitrogen filled antenna line leak testing use

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Measurement Unit Related Terms

More pages related to measurement unit technical terms.

• at – Technical Atmosphere Pressure Unit
• atm – Standard Atmosphere Pressure Unit
• bar Pressure Unit
• cmH2O – Centimetres of Water Column at 4 deg C Pressure Unit
• cmHg – Centimetres of Mercury at 0 deg C Pressure Unit
• daPa – Dekapascal Pressure Unit
• dyn/cm² – Dyne per Square Centimetre Pressure Unit
• ftH2O – Feet of Water Column at 4 deg C Pressure Unit
• g – Acceleration due to Gravity
• g/cm² – Grams per Square Centimetre Pressure Unit
• hPa – Hectopascal Pressure Unit
• inH2O – Inches of Water Column at 4 deg C Pressure Unit
• inHg – Inches of Mercury at 0 degrees C Pressure Unit
• kg/cm² – Kilogram per Square Centimetre Pressure Unit
• kg/mm² – Kilogram per Square Millimetre Pressure Unit
• kPa – Kilopascal Pressure Unit
• ksi – Kilopounds per Square Inch Pressure Unit
• mbar – Millibar Pressure Unit
• mH2O – Metres of Water Gauge at 4 deg C Pressure Unit
• mmH2O – Millimetres of Water Column at 4 deg C Pressure Unit
• mmHg – Millimetres of Mercury at 0 deg C Pressure Unit
• MPa – Megapascal Pressure Unit
• mPa – Millipascal Pressure Unit
• mTorr – Millitorr Pressure Unit
• N/cm² – Newton per Square Centimetre Pressure Unit
• N/m2 – Newton per Square Metre Pressure Unit
• N/mm² – Newton per Square Millimetre Pressure Unit
• oz/in² – Ounce per Square Inch Pressure Unit
• Pa – Pascal Pressure Unit
• Pressure
• Pressure Units
• psf – Pounds per Square Foot Pressure Unit
• Specific Gravity
• Torr Pressure Unit
• tsf – Tons per Square Foot (USA, Short) Pressure Unit
• tsi – Tons per Square Inch (UK, Long) Pressure Unit
• tsi – Tons per Square Inch (USA, Short) Pressure Unit
• Water Density
• µHg – Micron of Mercury at 0 deg C Pressure Unit