The bar is a metric pressure unit equal to 100,000 pascals, widely used in meteorology, oceanography, and industrial applications because it closely approximates atmospheric pressure at sea level. Tire pressure gauges in Europe, scuba diving depth ratings, and weather maps all commonly reference bars or millibars. One bar equals approximately 0.9869 atmospheres or 14.504 psi.

The millimeter of mercury (mmHg) is a pressure unit equal to about 133.322 pascals, traditionally used in medicine for measuring blood pressure and in meteorology for barometric readings. A normal adult blood pressure of 120/80 mmHg is universally understood by healthcare professionals, making this unit a fixture in clinical settings. One mmHg equals approximately 0.01934 psi or 0.1333 kPa.