gallon

American  

[gal-uhn] / ˈgæl ən /

noun

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.

---

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

---

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

---

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

“All of the flights are way more expensive than they used to be,” he said as he paid almost $5.80 per gallon at the 76 on Century Boulevard near Los Angeles International Airport.

From Los Angeles Times • Jun. 12, 2026

At about $4.11 a gallon to end the week, gasoline prices are down nearly 10% versus a month ago, according to AAA, but remain well above the $3.13 seen this time last year.

From The Wall Street Journal • Jun. 12, 2026

Oil’s current level should be enough for gasoline at the pump to fall below $4 a gallon by the end of June, Molchanov noted.

From MarketWatch • Jun. 12, 2026

Domestic airfares surging, hotel room rates soaring, and gas prices at the pump north of $4 a gallon is an ugly combination.

From Barron's • Jun. 11, 2026

That was enough to buy one gallon of Neapolitan ice cream, which she said was not only delicious but had lots of calcium and would be good for our bones.

From "The Glass Castle" by Jeannette Walls