Bar to Pound per Square Inch Formula
psi = bar × 14.503773773
Conversion factors follow SI relationships published by BIPM and NIST, where those standards apply.
Because 1 bar = 10⁵ Pa exactly (CIPM accepted value recorded in the SI Brochure) and 1 psi = 6 894.757293168 Pa. Reverse: bar = psi × 0.06894757293.
Bar to Pound per Square Inch Converter
Quick Answer
1 bar = 14.5038 psi
Formula: Pound per Square Inch = Bar x 14.5038
Quick values
Sources
- BIPM SI Brochure — Definitions of the pascal, watt, and other SI derived units.
- NIST Special Publication 811 — Guide for the Use of the International System of Units (SI), including appendix conversion factors.
- NIST SI units of pressure — Pascal (N/m²) is the SI pressure unit; bar = 10⁵ Pa is a non-SI unit accepted for use with the SI.
Worked examples
- 1 bar process line: 1 × 14.503773773 = 14.5038 psi
- 2.4 bar car tire (typical metric sticker): 2.4 × 14.503773773 = 34.8091 psi
- 10 bar hydraulic test: 10 × 14.503773773 = 145.038 psi
What is bar to psi?
One bar is exactly 100 000 Pa (100 kPa), a non-SI unit accepted for use with the SI. Dividing by the pound-force per square inch gives 14.503773773 psi.
Formulapsi = bar × 14.503773773
Key conversions
- 1 bar = 100 kPa = 14.5038 psi exactly from 10⁵ Pa
- 1 atm = 1.01325 bar = 14.6959 psi
- 1 psi = 0.0689476 bar
How many psi are in 1 bar?
One bar is exactly 100 000 pascals (100 kPa). Dividing that coherent SI value by 6 894.757293168 Pa/psi gives 14.503773773 psi. The bar is not an SI unit, but the SI Brochure still lists it as a non-SI unit accepted for use; hydraulics, pneumatics, and European process sheets use it constantly.
Treat “bar” as gauge unless the sheet says bar(a) or bara. A 2.5 bar compressor setpoint is 36.26 psi gauge. Standard atmosphere is 1.01325 bar, which is 14.6959 psi — slightly above 1 bar, so “1 bar ≈ 1 atm” is only a field approximation.
Category hub: Pressure Conversion · Conversion charts · Conversion formulas
Bar to Pound per Square Inch Conversion Table
Hydraulic, pneumatic, and atmospheric values that show up on nameplates
| Bar (bar) | Pound per Square Inch (psi) |
|---|---|
| 0.5 bar | 7.25189 psi |
| 1 bar | 14.5038 psi |
| 1.01325 bar | 14.6959 psi |
| 2 bar | 29.0075 psi |
| 2.4 bar | 34.8091 psi |
| 2.5 bar | 36.2594 psi |
| 4 bar | 58.0151 psi |
| 6 bar | 87.0226 psi |
| 8 bar | 116.03 psi |
| 10 bar | 145.038 psi |
| 20 bar | 290.075 psi |
| 50 bar | 725.189 psi |
| 100 bar | 1450.38 psi |
1.01325 bar is standard atmosphere (absolute). Other rows are typical gauge setpoints.
Browse all conversion charts → · Browse conversion formulas →
Practical use cases for Bar to Pound per Square Inch
Tire and Vehicle Service
Passenger-car tire placards in the US are often in PSI, while many gauges and shop manuals list kPa or bar. Converting before inflation avoids under- or over-pressurizing a tire.
HVAC and Hydronics
Boiler, chiller, and duct-pressure specs mix PSI, kPa, and inches of water. Field techs convert so setpoints match the equipment nameplate.
Process and Plant Engineering
P&IDs and relief-valve datasheets may use PSI, bar, or kPa depending on the region. Accurate conversion is required before sizing piping and safety devices.
Meteorology and Aviation
Altimeter and station-pressure reports use inHg, hPa, or kPa. Pilots and weather desks convert between those scales for briefings and QNH settings.
Medical and Laboratory Gases
Cylinder pressures and ventilator settings are published in different units by manufacturer and country. Clinicians convert to the unit on the local gauge.
Hydraulics and Pneumatics
Pump and compressor curves are often published in bar or kPa while US shop drawings stay in PSI. Converting keeps actuator force and regulator settings consistent.
Bar to Pound per Square Inch FAQs
Common questions about converting bar to pound per square inch.
Is 1 bar exactly 14.5 psi?
No. 1 bar = 14.503773773 psi. Rounding to 14.5 psi is about 0.026% low — acceptable on a tire sticker, not on a relief-valve set point. This page uses the full factor from 10⁵ Pa ÷ 6 894.757293168 Pa/psi.
What is the difference between 1 bar and 1 atmosphere?
1 atm is defined as 101 325 Pa = 1.01325 bar = 14.6959 psi. 1 bar is a round 100 kPa. They differ by 1.325 kPa (about 0.19 psi). Do not substitute one for the other in vacuum or altitude work.
Are bar and mbar the same family as psi?
Yes — all three are pressure. 1 bar = 1 000 mbar = 100 kPa. Weather reports in millibars convert to psi by dividing mbar by 68.9476, or convert mbar → bar first (÷ 1 000) then apply the bar-to-psi factor.
Does this converter add atmospheric pressure?
No. It only changes the unit. A 6 bar(g) manifold is 87.02 psi(g). If a US vendor wants psia, add local atmosphere after the conversion (about 14.7 psi at sea level).
Why do hydraulic catalogs list both bar and psi?
ISO 2944 and most CE-marked pumps use bar. North American fittings and gauges still use psi. Convert the rating, then confirm whether the catalog number is a nominal series (for example “1500 psi / 350 bar”) or a precise set pressure.
Charts and printable PDF
Use the matching bar / pound per square inch chart when you need a printable table or offline reference.
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