Pascals

The pascal (symbol Pa) is the SI unit of pressure, defined as one newton of force applied to one square meter of area. It is a derived unit in the International System of Units, representing force per unit area (1 Pa = 1 N/m^2). The pascal is used to quantify both actual pressure and mechanical stress.

The unit is named after Blaise Pascal, a 17th‑century French physicist who studied fluid pressure and hydrostatics. The pascal was adopted as part of the SI system in the mid-20th century and is widely used in science, engineering, meteorology, and everyday measurements of pressure.

Because the pascal is a small unit for typical pressures, many measurements use multiples or submultiples such as kilopascals (kPa) and megapascals (MPa). For example, 1 kPa equals 1,000 Pa and 1 MPa equals 1,000,000 Pa. In meteorology, the hectopascal (hPa) is commonly used, with 1 hPa equal to 100 Pa; standard sea‑level atmospheric pressure is about 1013 hPa (approximately 101,325 Pa). Other related values include 1 bar (100,000 Pa) and 1 atmosphere (about 101,325 Pa).

The pascal is used to express pressure in diverse contexts, including weather reports, tire inflation, hydraulics, vacuum technology, and material science. Instrumentation for measuring pressure includes barometers, manometers, and pressure transducers. Because pressure and stress share the same dimensional units, the pascal also serves as a convenient unit for describing mechanical stress in solids.