gallon

American  

[gal-uhn] / ˈgæl ən /

noun

• gallons
  plural

1. a common unit of capacity in English-speaking countries, equal to four quarts, the U.S. standard gallon being equal to 231 cubic inches (3.7853 liters), and the British imperial gallon to 277.42 cubic inches (4.546 liters). gal.

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gallon British  

/ ˈɡælən /

noun

1. Also called: imperial gallon.  a unit of capacity equal to 277.42 cubic inches. 1 Brit gallon is equivalent to 1.20 US gallons or 4.55 litres

2. a unit of capacity equal to 231 cubic inches. 1 US gallon is equivalent to 0.83 imperial gallon or 3.79 litres

3. (plural) great quantities

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gallon Scientific  

/ găl′ən /

1. A unit of liquid volume or capacity in the US Customary System equal to 4 quarts (3.79 liters).

2. See Table at measurement

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Other Word Forms

Noun Inflected Forms

• gallons
  plural

Etymology

Origin of gallon

First recorded in 1250–1300; Middle English galo(u)n, gallon, from Old North French galon, derivative from base of Medieval Latin gallēta “jug, bucket,” of uncertain origin

Compare meaning

How does gallon compare to similar and commonly confused words? Explore the most common comparisons:

• gallon vs. liter
• pint vs. gallon

Explanation

The gallon is a unit of measurement used for liquids such as gasoline, water, and milk in the United States. If your car’s tank is running on empty, then you better pull over and buy at least a few more gallons of gas. A gallon is equivalent to 4 quarts of liquid or 3.785 liters. The United States is one of the last countries to use this term. Though the gallon has roots in the British Imperial Units measurement system, the United Kingdom and most countries around the world have switched to the newer International System of Units.

Example Sentences

See Examples For:

gallon gallons

By then, a gallon of gas averaged around $4.50, according to AAA.

From Salon ● Aug. 23, 2026

The giant US retailer steered much of the benefit from US tariff refunds towards investments to attract inflation-strapped customers, who faced gasoline prices above $4 a gallon for much of the quarter.

From Barron's ● Aug. 20, 2026

The conflict has caused gas prices in the US to spike to above $4 a gallon, a painful hike to any US business that relies on transport.

From BBC ● Aug. 12, 2026

In California, a gallon of gasoline averaged about $5.60 on Monday, the highest price of any state in the country.

From The Wall Street Journal ● Aug. 11, 2026

With a shake of the head, Saidu picked up the gallon of water and started heading down the path.

From "A Long Way Gone: Memoirs of a Boy Soldier" by Ishmael Beah

Diablo Canyon uses 2.5 billion gallons of ocean water for cooling each day, discharging hot water directly into the nearby cove.

From Los Angeles Times ● Aug. 16, 2026

The proposed center in Nodaway County, about 40 miles from here, would use municipal wastewater in a closed-loop cooling system that, according to the project website, requires an initial 1.5 million gallons.

From The Wall Street Journal ● Aug. 14, 2026

Their individual payloads of more than 1,000 gallons of water are then dumped onto the flames below.

From BBC ● Jul. 29, 2026

The break left a giant sinkhole on Sunset Boulevard and sent about 17 million gallons of water into surrounding neighborhoods, shuttering businesses, and flooding homes and underground parking.

From Los Angeles Times ● Jul. 25, 2026

It was impossible to guess how many gallons but it had to be at least a hundred.

From "The Voyage Of The Frog" by Gary Paulsen