ucUnitCloudInternational unit matrix

Mistake guide

Using 14.5 instead of 14.7 for bar and psi

1 bar is 14.5 psi.

01Assumption

1 bar is 14.5 psi.

02Actually

1 bar = 100000 Pa and 1 psi = 6894.757293168361 Pa, so 1 bar ≈ 14.5037737730 psi. The frequently quoted 14.7 belongs to the atmosphere, not to the bar: 1 atm = 101325 Pa ≈ 14.6959487755 psi.

03Why

Bar and atmosphere differ by only about 1.3 % and are used interchangeably in everyday speech. That mixes up their psi values, and 14.5038 easily becomes 14.7.

04Check

If a conversion factor falls between 14.5 and 14.8, first establish which source unit is meant. With pressure figures also check whether absolute pressure or gauge pressure relative to the atmosphere is intended — the difference is about 1 bar.

Matching conversions

bar to psibar → psiPressurepsi to barpsi → barPressureAtmosphere to psiatm → psiPressurepsi to Atmospherepsi → atmPressurebar to Kilopascalbar → kPaPressure

Matching tables

TableTyre pressure: bar, psi and kPa

Unit family: Pressure

Sources

BIPM SI BrochureSI base units, prefixes and official SI context.NIST Guide to SI Appendix BNIST conversion-factor method and non-SI factors.
When not to use

Do not use as the sole basis for official, medical, safety-critical or contractual decisions.

Citation

Citation note: UnitCloud, mistake guide, sources reviewed: September 2026. Source basis: BIPM SI Brochure · NIST Guide to SI Appendix B.