Imperial and US customary measurement systems
Two related systems of measurement derived from English units.
The imperial and US customary measurement systems are both derived from an earlier English system of measurement, which in turn can be traced back to Ancient Roman units of measurement, and Carolingian and Saxon units of measure.
- Origin
- Derived from English units, with roots in Roman, Carolingian, and Saxon measures
- US Customary system developed
- After the American Revolution
- Primary region for US Customary
- United States and its territories, except Puerto Rico and Guam
- Primary region for Imperial
- United Kingdom and its empire
- Common definitions agreed
- 1960, based on the metre and kilogram
Lore & Background
The imperial and US customary measurement systems both evolved from English units, which were themselves a combination of Roman, Carolingian, and Saxon measures. The US Customary system was developed after the American Revolution, using a subset of English units from the Thirteen Colonies. The foot used by craftsmen supplanted a longer agricultural foot, which was reduced to 10/11 of its former size, causing the rod to become 16.5 rather than 15 agricultural feet.
Reader's Guide
The imperial and US customary systems are significant as the predominant measurement systems in the United Kingdom and United States respectively, though the metric system has replaced the imperial system to varying degrees in former British empire countries. The legacy of these systems includes ongoing use in the US and occasional use in the UK, alongside metric units.
Did You Know?
- In 1960, the US and UK agreed to common definitions of the yard and pound based on the metre and kilogram.
- The US Customary system is predominant in the United States and its territories, except Puerto Rico and Guam.
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