Read across two unit systems
One bar equals 100,000 pascals, or approximately 14.5037738 PSI. Convert bar to PSI by multiplying by 14.5037738. Convert PSI to bar by dividing by that number. For everyday specification comparisons, 90 PSI is approximately 6.21 bar and 6 bar is approximately 87.02 PSI.
Use the unrounded value for calculations and round the display for readability. A manufacturer may round 90 PSI to 6.2 bar. That small display difference does not necessarily describe a separate operating condition.
Preserve the pressure reference
Gauge pressure is measured relative to the surrounding atmosphere; absolute pressure is measured relative to a vacuum. Converting the units does not convert one reference into the other. A value entered as gauge PSI becomes gauge bar. Look for markings such as PSIG, PSIA, barg or bara when the distinction matters.
For an illustrative comparison, a fictional tool requiring 6.2 bar is requesting roughly 89.92 PSI on the same pressure reference. That conversion helps you locate a relevant compressor rating; it does not establish that the tool actually receives that pressure through the installed hose.
Working pressure is the buying question
A compressor’s maximum pressure, switch settings, regulator setting and the tool’s specified operating pressure have different roles. Keep each number in its own field. Do not substitute a high maximum tank pressure for the missing airflow rating at the pressure your tool needs.
If a tool’s required pressure is above the compressor’s stated maximum, that is a clear specification conflict. If it is below the maximum, more checks remain: delivered airflow at the relevant pressure, regulation, the air line and the manufacturer’s operating limits. The converter is a reading aid, not an instruction to adjust equipment pressure.
A pressure conversion preserves what was measured. A maximum tank rating remains a maximum tank rating after conversion.