Short answer
bar, MPa and psi are pressure units used for the same physical quantity. Changing the unit does not change the strength of the product or the permitted working limit. The distinction between absolute pressure and gauge pressure is also independent of unit conversion.
Source: S023
Technical explanation
According to NIST conversion data, 1 bar = 100,000 Pa and 1 MPa = 1,000,000 Pa, so 1 MPa = 10 bar. The psi conversion is based on the definitions of pound-force and square inch; approximately 6,894.757293 Pa is used for 1 psi in the calculation. Display rounding may be applied, but working and test pressure fields must be kept separate in meaning even when they are in the same unit.
Source: S023
Topic-specific checkpoints
| Item | Description |
|---|---|
| bar → MPa | Value ÷ 10 |
| MPa → bar | Value × 10 |
| bar → psi | Approximately value × 14.503774 |
| Meaning | Working/test and absolute/gauge distinctions are preserved |
Source: S023
How to evaluate it in practice
In the calculation tool, make selection of the input and output units mandatory. For example, 10 bar = 1 MPa and approximately 145.038 psi. This example is not a working pressure recommendation. When transferring the result, also preserve whether the source value is gauge or absolute; converting between these two requires a reference pressure. The unit converter preserves the sign of negative gauge values. However, it does not classify vacuum or convert gauge pressure to absolute pressure.
Original editorial recommendation; not a clause of a standard.
Frequently asked questions
Does converting 200 bar to psi allow a higher pressure?
No. The larger number is only a change of unit; the physical pressure and the product limit do not change.
Source: S023
Source coverage
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S023
NIST Guide to the SI, Appendix B.8 NIST · accessed 2026-10-19 Alphabetical entries: bar, inch, pound-force per square inch