SIprefixin

SIprefixin is a wiki-style reference that documents the prefixes used in the International System of Units (SI) and their practical application. It serves as a neutral, collaborative resource intended for students, researchers, and professionals who seek clear guidance on how prefixes attach to base and derived units and how they are represented in text and notation.

Origin and scope: The project emerged as a community-edited compendium in the early 2020s. While its articles draw on official SI definitions and widely accepted usage, SIprefixin is not an official standard or regulator. It aims to summarize conventions, provide concrete examples, and record language- and context-specific notes.

Content and organization: Entries cover the full set of established SI prefixes from yocto to yotta, including symbol conventions, magnitude, and typical contexts of use. The resource also explains capitalization, spacing, prefix stacking rules, and how prefixes interact with multiple units or complex notations. Multilingual renderings and common pitfalls are often included.

Usage and examples: The site presents representative examples such as 1 km (one kilometer), 5 μs (five microseconds), and 3 MW (three megawatts) to illustrate standard usage. It also discusses how prefixes may be written in plain text, with Unicode symbols or ASCII substitutes, and cautions against ambiguous combinations.

Community and governance: As a user-edited platform, SIprefixin relies on crowd-sourced contributions, citations, and editorial oversight to maintain accuracy and neutrality. It adheres to a permissive license for reuse and discourages misinformation.

See also: International System of Units, SI prefixes, BIPM, metrology, units of measurement.