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Pressure Conversion Calculator (psi, bar, MPa, kPa)

Hydraulic pumps, pneumatic regulators, test rigs and vessels are rated in psi, bar, MPa, kPa or kgf/cm2 depending on the country and the age of the equipment. This calculator converts between them with exact definitions.

Your numbers

Pressure value

Gauge or absolute, as written on the spec. The converter does not change the reference.

Convert from

Your results

Bar

6.8948

psi

100

Pascal (Pa)

689,475.7

Kilopascal (kPa)

689.4757

Megapascal (MPa)

0.6895

Standard atmosphere (atm)

6.8046

kgf/cm2

7.0307

mmHg (torr)

5,171.4931

Unit conversion only. Gauge versus absolute reference is not converted. Pressure vessel and piping design must follow the applicable code and manufacturer ratings.

Save results:

bar and psi for the same pressure

Sweeps Pressure value from 10 to 400, holding your other inputs fixed.

Maintenance plan unit review

Optional: we can scan PM plans for pressure and torque values written in mixed units.

Optional. The tool and every export work without this. No spam.

How to use the calculator

Type the pressure value, choose the unit it is written in, and read bar, psi, kPa, MPa, atm, kgf/cm2 and mmHg in the results. Everything is first converted to pascals and then to each target unit, so there is no chaining error. The chart plots bar against psi over a range, which helps when you are printing a gauge card or checking a test plan for a mixed-unit fleet.

Quick rule: 1 bar is about 14.5 psi
1 MPa equals 10 bar equals 145 psi
kgf/cm2 is within about 2 percent of bar
Match your gauge range to the converted value

Definitions and factors

One bar is exactly 100,000 Pa. One standard atmosphere is exactly 101,325 Pa. One psi is 6894.757 Pa, defined from the pound-force and the inch. One kgf/cm2 is 98,066.5 Pa from standard gravity, and one mmHg is 133.322368 Pa. Inches of water depend on the reference temperature, so the factor used here is the 60 F convention.

Worked example

A hydraulic press manual rates a relief valve at 210 bar. Entering 210 bar returns 3,046 psi and 21 MPa. A European test spec of 6 bar converts to 87 psi, so a US regulator with a 0 to 100 psi gauge would be suitable but with limited headroom. For sizing, choose a gauge with the operating pressure around 50 to 70 percent of the full scale range.

Common mistakes

The classic error is ignoring gauge versus absolute: psig is relative to local atmosphere while psia is relative to vacuum, so 100 psig is about 114.7 psia. Others are treating bar and kgf/cm2 as identical in a critical test, confusing kPa and MPa by a factor of 1,000, and reading vacuum values in mmHg as positive pressures.

Always record gauge or absolute with the value
Vacuum specs are often in mmHg, torr or kPa absolute
Do not exceed the lowest-rated component in the circuit
Hydrostatic test pressure is a code multiple of design pressure

Frequently Asked Questions

How many psi is 1 bar?

One bar equals 14.5038 psi. For quick shop-floor math use 14.5, so 6 bar is about 87 psi and 10 bar is about 145 psi.

How do I convert MPa to psi?

Multiply MPa by 145.038. For example, 25 MPa is about 3,626 psi. Going the other way, divide psi by 145.038.

Is bar the same as kgf/cm2?

Almost, but not exactly. One kgf/cm2 equals 0.980665 bar, about 2 percent lower. Older Japanese and Indian equipment documents often use kgf/cm2, so convert before ordering parts or setting relief valves.

What is the difference between psig and psia?

Psig is measured relative to ambient atmosphere, psia relative to absolute vacuum. At sea level, psia equals psig plus about 14.7. Specs must say which one applies, especially for compressors and vacuum systems.

If your preventive maintenance plans store pressure settings in mixed units, Netray can help build a read-only check across your ERP and CMMS data. Ask for a scoping call.

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