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Technical Glossaries

Measurement Abbreviations & Symbols

Standard symbols, abbreviations, and formatting guidelines for imperial and metric units of length.

1. Imperial Units of Length

Imperial units are primarily utilized in the United States, and historically across the United Kingdom. Standard symbols and shorthand representations include:

  • Inch (in, "): The standard unit symbol is `in`. Alternatively, the double prime symbol " is commonly used in drafting and shop drawings (e.g. 12" represents 12 inches).
  • Foot (ft, '): The standard abbreviation is `ft`. The single prime symbol ' represents feet in shorthand layouts (e.g. 5' 9" means 5 feet 9 inches).
  • Yard (yd): The standard abbreviation is `yd`. One yard contains exactly 3 feet or 36 inches.

2. Metric (SI) Units of Length

Metric units are decimal-based, governed by the Bureau International des Poids et Mesures (BIPM). Standard unit symbols include:

  • Meter (m): The base unit of length in the SI system. The symbol is always a lowercase `m`. Note that US English writes "meter", while UK/International English writes "metre".
  • Centimeter (cm): One-hundredth of a meter (`1 cm = 0.01 m`). The standard symbol is `cm`.
  • Millimeter (mm): One-thousandth of a meter (`1 mm = 0.001 m`). The standard symbol is `mm`.

3. Quick Formatting Guide

Under NIST SP 811 guidelines, proper technical writing requires maintaining specific formatting rules:

  • Do not append an "s" to symbols for plurals (e.g., write 10 m, not 10 ms).
  • Always leave a space between the numerical value and the unit symbol (e.g., 50 mm, not 50mm).
  • Do not place a period after unit symbols unless they occur at the end of a sentence.