Imperial units facts for kids

The Imperial units or the Imperial system is a collection of measurement units. An Act of Parliament in 1824 created it from traditional English units. Commonwealth countries used this system from 1824 until they changed to the metric system. The imperial system is very similar to the American system but there are some differences.

Measuring Length in Imperial Units

Imperial units use different names for measuring how long things are. These include inches, feet, yards, and miles. You might still hear these used today, especially for things like height or road distances.

Common Length Units Explained

• Inch: This is a small unit, about the length of your thumb from the knuckle to the tip.
• Foot: A foot is made of 12 inches. Many people use feet to measure their height.
• Yard: A yard is longer, equal to 3 feet or 36 inches. Sports like American football use yards to measure the field.
• Mile: This is a very long unit, used for measuring distances between places. One mile is the same as 1,760 yards, or 5,280 feet.

Nautical Miles

There's also a special unit called the nautical mile. It was used for measuring distances at sea. The British nautical mile used to be 6,080 feet. But in 1970, the UK started using the international definition, which is 1,852 metres.

Measuring Area in Imperial Units

Area tells us how much flat space something covers. Imperial units for area include the square foot and the acre.

Understanding Area Units

• Square Foot: This is a small unit for area. Imagine a square that is one foot long on each side; that's one square foot.
• Acre: An acre is a much larger unit, often used for measuring land. It's about the size of a football field. One acre is equal to 43,560 square feet.

Measuring Volume in Imperial Units

Volume tells us how much space a liquid or dry item takes up. Imperial units for volume include fluid ounces, gills, pints, quarts, and gallons.

Liquid Volume Units Explained

Here's how some common liquid volume units relate to each other:

• Fluid Ounce: This is a small amount of liquid. You might see it on drink bottles.
• Pint: A pint is 20 fluid ounces. Milk and juice are often sold in pints.
• Quart: A quart is twice as big as a pint, so it's 2 pints.
• Gallon: A gallon is the largest common unit for liquids, equal to 4 quarts or 8 pints. Fuel for cars is often measured in gallons.

For a comparison to the United States customary units see the article on Comparison of the Imperial and US customary systems.

Measuring Mass and Weight in Imperial Units

Mass and weight tell us how heavy something is. Imperial units for this include grains, ounces, pounds, stones, hundredweights, and tons.

Common Mass and Weight Units

Here's how these units relate to each other:

• Ounce: A small unit of weight. You might see it used for food items.
• Pound: A pound is 16 ounces. Many foods, like meat or fruit, are sold by the pound.
• Stone: This unit is often used for a person's weight in the UK. One stone is equal to 14 pounds.
• Ton: A ton is a very large unit of weight, used for very heavy things like cars or trucks. One ton is 2,240 pounds.

Related Pages

• International System of Units

• Jacques J. Proot's Anglo-Saxon weights & measures page.

Images for kids

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  The former Weights and Measures office in Seven Sisters, London (590 Seven Sisters Road)

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  Imperial standards of length 1876 in Trafalgar Square, London.

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  All units of length defined by Appendix C of the NIST Handbook

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  A one US gallon gas can purchased near the US-Canada border showing equivalences in imperial gallons and litres

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  Imperial and metric measurements on Canadian canned goods labels. The imperial measurements often take precedence over the metric ones on labels.