1 bar = 100 kPa = 14.5038 PSI. 1 atmosphere = 101.325 kPa = 14.696 PSI = 760 mmHg. 1 PSI = 6.89476 kPa = 0.0689 bar.
Example: a car tire at 32 PSI is 2.21 bar or 220.6 kPa.
One bar is about 14.504 PSI. Multiply bar by 14.5 to estimate PSI.
Most passenger cars run 2.0 to 2.5 bar (29 to 36 PSI); check the sticker inside the driver door for your vehicle.
See also: temperature converter · length converter · weight converter