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

The 2008 peak of $4.74 a gallon is equivalent to $7.20 in today’s dollars, while the more recent 2022 peak of almost $5.82 would be about $6.56 today.

From Los Angeles Times ● Sep. 4, 2026

In a reminder of the inflation pressure facing the Fed, diesel prices hit a new all-time high of $5.85 a gallon on Friday, surpassing their previous record from 2022.

From The Wall Street Journal ● Sep. 4, 2026

For example, in Washington, average diesel prices are $6.81 a gallon, compared to $5.03 a gallon a year ago.

From BBC ● Sep. 4, 2026

Inflation-adjusted diesel prices have reached higher than the current $5.85 national average per gallon.

From Los Angeles Times ● Sep. 4, 2026

He and Roberto wrapped the gallon water bottle with burlap and sewed it tightly to keep the bottle from breaking.

From "The Circuit: Stories from the Life of a Migrant Child" by Francisco Jiménez

That sounds staggering until you put it in context: Agriculture uses vastly more water—81 million acre-feet, or 2.6 trillion gallons, of irrigation water in 2023.

From The Wall Street Journal ● Aug. 25, 2026

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

Investigators linked the tanker to 2.6 million gallons of Texas diesel falsely labeled as lubricating oil additives.

From Los Angeles Times ● Aug. 3, 2026

This morning Mom discreetly gave away a couple of gallons to some friends around the corner.

From "Dry" by Neal Shusterman and Jarrod Shusterman