Logo of the Physikalisch-Technische Bundesanstalt

A short history of the SI prefixes

Abschiedskolloquium für Dr. Bernd Güttler

The International System of Units (SI) is the world’s measurement system. A key part of the SI is the SI prefixes, which are used together with units when measurements get very big or very small, to ensure the results expressed remain easy to understand and communicate, especially across technical disciplines.

This presentation describes the history and development of the SI prefixes and explains the story behind the recent addition to the range of SI prefixes at the 27th General Conference on Weights and Measures in November 2022 - which added quetta, ronna, ronto and quecto for 1030, 1027, 10-27 and 10-30, respectively - principally to meet the future requirements of data science and increased digitalisation.

The talk concludes with a brief consideration of the possible future development of the SI prefixes.