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

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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

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Compare meaning

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

• gallon vs. liter
• pint vs. gallon

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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

Average on-highway price for a gallon of diesel in the week ended Oct.

From The Wall Street Journal ● Oct. 21, 2026

She finds discounts with Harris Teeter fuel points or uses the free Walmart+ subscription through her American Express Platinum card that offers 10 cents off a gallon at some pumps.

From MarketWatch ● Oct. 20, 2026

Note: All prices are for a pound, except eggs and milk, which are for a dozen and gallon, respectively.

From The Wall Street Journal ● Oct. 18, 2026

A year ago, diesel was $3.66 a gallon, on average.

From MarketWatch ● Oct. 14, 2026

The electric lantern was already beginning to dim and he looked through the stores until he found some cases of white gas in gallon cans.

From "The Road" by Cormac McCarthy

A large line that broke on July 16 sent millions of gallons of water onto the Sunset Strip, causing a massive sinkhole and forcing city officials to shut down Sunset Boulevard and other side streets.

From Los Angeles Times ● Oct. 14, 2026

Household heating-oil fuel tanks hold about 275 gallons, with a medium-sized home getting around three deliveries of 200 gallons each per year, he said.

From MarketWatch ● Oct. 10, 2026

Energy assistance comes in the form of U.S. dollars, not gallons, so with the higher prices for heating oil, ‘those dollars are only going to go half as far as they did a year ago.’

From MarketWatch ● Oct. 10, 2026

The company claims it produced 19 million US gallons of water in the sky in three hours.

From BBC ● Oct. 7, 2026

Then twelve billion gallons of water molecules crowd for that initial escape vent, and they tear and chew at the structure until house-size chunks of it tumble down its disintegrating face.

From "100 Sideways Miles" by Andrew Smith

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