Hectopascale

A hectopascal, denoted as hPa, is a unit of pressure in the International System of Units (SI). It is equal to 100 pascals. The pascal itself is defined as one newton per square meter (N/m²). Therefore, a hectopascal represents 100 newtons of force applied over one square meter of area.

The hectopascal is commonly used in meteorology for measuring atmospheric pressure. Weather forecasts and station reports often express atmospheric pressure in hectopascals. Standard atmospheric pressure at sea level is approximately 1013.25 hectopascals. This is equivalent to 101,325 pascals or 101.325 kilopascals.

The relationship between hectopascals and other common pressure units can be useful. One hectopascal is equal to 0.001 bar. It is also approximately equal to 0.0145 pounds per square inch (psi). Historically, millibars (mb) were frequently used in meteorology, and one millibar is exactly equal to one hectopascal. The transition to hectopascals has largely standardized meteorological pressure measurements within the SI framework.