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.

• 1.5 psi wet/wet DP transmitter for line pressures up to 1,885 psi
• Oxygen clean 300 psig range 4-20mA output ceramic diaphragm pressure sensor
• Brake line pressure sensor to measure up to 4000 psi g with 0-10Vdc signal
• 15,000 psi intrinsically safe high pressure logger

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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.

• R22 and R410A refrigerant compatible 400 psi g pressure transmitter
• 600 bar, 9000 psi, 60 MPa Pressure Sensors, Transducers & Transmitters
• Salt water pump pressure sensor & gauge with 250 psi range
• Pressure gauge and hand pump for calibrating up to 150psi?

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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

• Data logger for ATEX zone 1 area to measure up to 5000 psi
• Inexpensive pneumatic 15-300 psig range 0-5Vdc output pressure sensor
• Liquid compatible transmitter with 15 psi DP range and protected on either side to 300 psi
• 40 ksi g 4-20mA freshwater pressure sensor plus display for hydrothermal testing use

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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

• 200 psi g HVAC/R pressure transducer with 0.5-4.5Vdc ratiometric output
• R21/R22 refrigerant digital pressure gauge to read up to 500psi
• 3000 psig RS485 ModbusRTU interface synthetic hydraulic oil pressure sensor for testing use
• 100 psig range landfill leachate pressure gauge with 4-20mA output for SCADA sytem

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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

• Vacuum and steamer pressure transducer with -30 inHg to 100 psi range
• -15psig 0-10V out negative pressure transducer and display for air extraction use
• 10000 psig range USB output mineral hydraulic oil pressure sensor for component testing use
• 5000 psi WECO® 1502 pressure transmitter and loop indicator

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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.

• R21/R22 refrigerant digital pressure gauge to read up to 500psi
• 10000 psig range USB output mineral hydraulic oil pressure sensor for component testing use
• Minus 15 psi gauge intrinsically safe pressure transmitter
• 15psi dp range 4-20mA air pressure sensor for chamber airflow testing use on a 15psi line

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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