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This content has been automatically translated from Ukrainian.
US customary system — is a system of measures used in the United States of America. It originates from the English imperial system (Imperial units), but does not fully coincide with it. Its roots trace back to the colonial era: in the 17th–18th centuries, British settlers brought their measures and weights to North America. After the declaration of independence in 1776, the country retained traditional units but gradually adapted them to its own standards.
In the 19th century, Europe was transitioning en masse to the metric system, however, the US decided to stick with familiar units as the population and businesses were reluctant to change everyday habits.
Structure of the system
Unlike the metric system, the US customary system is not based on the decimal principle. Most units are related through "non-standard" ratios, making the system less convenient for calculations but historically understandable for its users.
Main examples:
-
Length:
- 1 foot = 12 inches,
- 1 yard = 3 feet,
- 1 mile = 1760 yards (or 5280 feet).
-
Mass and weight:
- 1 pound = 16 ounces (≈ 453.6 g),
- 1 ton (US ton) = 2000 pounds.
-
Volume:
- 1 gallon = 4 quarts = 8 pints = 128 fluid ounces (≈ 3.785 l),
- 1 pint = 16 fluid ounces (≈ 473 ml).
- Temperature: uses the Fahrenheit scale, where 32 °F corresponds to the freezing point of water, and 212 °F to boiling.
Most units in the US customary system originate from medieval Europe, where measurements were made "by eye" — based on the length of body parts, the size of objects, or common containers.
- Foot — originally equaled the average length of a human foot. In different countries, the "foot" could vary (from 25 to 34 cm). Only in the 19th century was it standardized to 30.48 cm.
- Inch — the word comes from the Latin uncia ("one twelfth"). Originally, an inch was equal to the width of a man's thumb. Later, it was defined as the length of three barley grains placed side by side. Today, an inch has a precise definition — 2.54 cm.
- Yard — according to legend, it was introduced by English King Henry I in the 11th century, defining a yard as the distance from his nose to the tip of his outstretched arm. Now, a yard is 91.44 cm.
- Mile — comes from the Latin mille passus — "a thousand paces." In Ancient Rome, it was a length of approximately 1.48 km. The English mile that reached the US was later established as 5280 feet (≈ 1.609 km).
- Pound — comes from the Latin libra pondus ("weight of a pound"). In Ancient Rome, a pound was approximately 327 g, but over time it varied in different countries. The modern American pound = 453.6 g.
- Ounce — also from Latin (uncia — "one twelfth"). Originally, an ounce was 1/12 of a Roman pound, now the American ounce equals ≈ 28.35 g.
- Gallon — originated in medieval England as a measure for wine and beer. In different regions, the gallon had a different volume, depending on what was being measured. In the US, the gallon was standardized as 3.785 l, while in the UK it is larger — 4.546 l.
- Pint — from English means "small part." Its volume also once varied from region to region. In the US, a pint = 473 ml, in Britain — 568 ml.
Thus, this system preserves ancient, "everyday" units related to the human body or practical measures of life. That is why it is considered less "logical" than the metric system, but at the same time closer to everyday perception.
Differences from the British imperial system
Although the US customary system originates from British measures, there are differences between them. For example, the gallon in the US is smaller than in the UK:
- 1 US gallon = 3.785 l,
- 1 Imperial gallon = 4.546 l.
Because of this, even English-speaking countries sometimes have difficulties in mutual understanding when it comes to measurements.
Where it is used today
The US is the only major country in the world that has not officially switched to the metric system. However, even within the States, the situation is heterogeneous:
- in science, medicine, and the military, metric units are actively used;
- in business, trade, and everyday life — the US customary system;
- in manufacturing and engineering, "dual standards" are often applied.
Canada, the United Kingdom, and some other countries are officially metric, but for certain areas (for example, beer in pints or height in feet) they have also retained imperial measures.
The US customary system is not just a set of units, but a cultural symbol for Americans. It is part of national identity and the "American way of life." At the same time, its parallel existence with the metric system creates difficulties in international trade and science.
Despite this, the US remains one of the few "islands" where the familiar foot, pound, and gallon will coexist with meters and liters for a long time.
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