Gallon facts for kids
A gallon is a unit of measurement used to figure out how much volume something takes up, especially liquids. Think of it like measuring how much milk is in a carton or how much gasoline is in a car's tank. People have used different kinds of gallons for a long time, and even today, there are a few main types still in use around the world.
Contents
What is a Gallon?
A gallon helps us measure liquids like water, milk, or fuel. It's a way to know the exact amount of space a liquid fills. For example, when you buy a gallon of milk, you know exactly how much you're getting.
Throughout history, different countries and even different regions within a country had their own versions of the gallon. This could sometimes be confusing! Today, the most common gallons you'll hear about are the imperial gallon and the U.S. wet gallon.
Different Kinds of Gallons
Even though they share the name "gallon," these units are not the same size. It's important to know which one people are talking about!
The Imperial Gallon
The imperial gallon was once widely used in the United Kingdom and other countries that were part of the British Empire. While it's not officially used for trade in the UK anymore, you might still hear it mentioned.
- One imperial gallon is equal to about 4.546 litres.
- It's also about 1.2 times bigger than a U.S. wet gallon.
- Interestingly, an imperial gallon of pure water at room temperature weighs exactly 10 pounds!
The U.S. Wet Gallon
The U.S. wet gallon is the most common type of gallon used in the United States. This is the gallon you'll see when you buy gasoline, milk, or other liquids.
- One U.S. wet gallon is exactly 3.785411784 litres.
- It's smaller than an imperial gallon, about 0.83 imperial gallons.
- This gallon is based on a specific volume: 231 cubic inches. Imagine a box that is 3 inches by 7 inches by 11 inches – that's one U.S. wet gallon!
- A U.S. wet gallon of pure water at room temperature weighs about 8.33 pounds.
The U.S. Dry Gallon
There's also a U.S. dry gallon, but it's not used very often today. It was historically used for measuring dry goods like grains or fruits.
- One U.S. dry gallon is equal to about 4.405 litres.
- It's slightly larger than the U.S. wet gallon.
- It's also a bit smaller than an imperial gallon, about 0.97 imperial gallons.
Why Are There Different Gallons?
The different sizes of gallons came about because of history and how measurements developed in different places. Before there were worldwide agreements on measurements, countries and even towns often created their own systems. Over time, some of these systems, like the imperial system and the U.S. customary system, became more common in certain parts of the world.
Today, most countries use the International System of Units (SI), which includes the litre for measuring volume. However, the gallon is still a very important unit in places like the United States.
Images for kids
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A Shell petrol station selling 2* and 4* (leaded petrol) by the gallon in the UK, circa 1980
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A fuel station in the United States displaying fuel prices per US gallon
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An American milk bottle with a volume of one US gallon
See also
In Spanish: Galón para niños
