attopascal [aPa] Unit Converter

Definition of attopascal [aPa] unit

An attopascal (aPa) is an SI unit of pressure equal to one quintillionth of a pascal, or 10−18 pascals. It quantifies extremely small pressures and is far below pressures encountered in ordinary environments.

History of attopascal [aPa] unit

The prefix atto- was introduced through the SI metric-prefix system in 1964, when the 11th General Conference on Weights and Measures adopted a set of prefixes extending measurement into extremely small and large powers of ten. “Atto” denotes 10−18 and derives from the Danish word atten, meaning eighteen. The pascal itself was named for French mathematician and physicist Blaise Pascal and became an SI derived unit in 1971. Thus, the attopascal combines an established pressure unit with a later prefix for ultrafine scientific measurements.

Applications of attopascal [aPa] unit

Because an attopascal is extraordinarily small, it is uncommon in routine engineering or weather reporting. It can describe pressure fluctuations in precision experiments, such as ultra-sensitive acoustic, quantum, and nanomechanical measurements, where researchers study minute forces or molecular interactions. The unit may also appear in theoretical physics, metrology, and specifications for instruments designed to detect exceptionally weak pressure signals.

Complete list of attopascal [aPa] unit conversion