Spelling of Metric Units

Controversies arise sometimes over the spelling of metric units. In many cases, these controversies grow out of a misunderstanding as to just what is international in the International System of Units (SI).

The fact is that the spellings of SI units vary from one language to another. In the case of the U.S. and Britain, spellings differ even within a language: Americans write meter and liter while the British write metre and litre.

The variation in spelling, however, goes much farther than that. Even if we disregard accent markings, the fundamental SI unit of length has numerous spellings, including:

No doubt this list could be extended quite a bit. The point is, there is no "official" spelling of the SI units. What the SI does provide includes the names, the definitions, and the symbols of the units. The words meter, metr, metre, etc. represent the same name spelled in different languages.

Within the International System, Russians are welcome to call 1000 meters a kilometr, but they cannot call it a verst, because that would be a different name. The Italians call the same unit the chilometro, but they cannot make its symbol chm; they must use km.


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All material in this folder is copyright 2018 by Russ Rowlett and the University of North Carolina at Chapel Hill. Permission is granted for personal use and for use by individual teachers in conducting their own classes. All other rights reserved. You are welcome to make links to this page, but please do not copy the contents of any page in this folder to another site. The material at this site will be updated from time to time.

June 4, 1999. Revised April 27, 2018.