Scope
Names, symbols, and definitions for quantities and units used in information science and technology — information content, entropy, transfer rates, storage capacity, and prefixes for binary multiples.
What You'll Find
One of two IEC-published parts — explicitly bilingual (English and French)
Defines binary prefixes: kibi (Ki), mebi (Mi), gibi (Gi), tebi (Ti), pebi (Pi), exbi (Ei), zebi (Zi), yobi (Yi)
Second edition adds robi (Ri) for 2⁹⁰ and quebi (Qi) for 2¹⁰⁰, matching the new SI prefixes ronna and quetta adopted at the 2022 CGPM
Succeeds subclauses 3.8 and 3.9 of IEC 60027-2:2005, the earlier standard for letter symbols in electrical technology
Obtain the Standard
Published by the International Electrotechnical Commission (IEC). Edition 2025 (2nd). Developed by IEC/TC 25 — Quantities and units.
Browse Entries
84 quantities defined in Part 13