What is a US Gallon?
The US gallon is the standard unit for fuel, milk, and beverages across the United States.
Overview
The US liquid gallon equals exactly 3.785411784 liters and is the standard volume unit for fuel, beverages, milk, and household liquids in the United States. Defined as 231 cubic inches, the US gallon descends from the English wine gallon of 1707, which Britain replaced with the larger imperial gallon in 1824 — a divergence that left the United States with a different gallon than the rest of the English-speaking world. American gas stations price gasoline by the gallon (typical fill-up: 12–15 gallons), milk is sold in half-gallons and gallons, and many beverages come in fluid-ounce subdivisions of the gallon. The US gallon relates to the liter (1 gal ≈ 3.785 L), the quart (4 qt = 1 gal), the pint (8 pt = 1 gal), the cup (16 cups = 1 gal), and the imperial gallon (1 imp gal ≈ 1.201 US gal — about 20% larger).
Convert US Gallon to all units
Live resultRelationship to Other Volume Units
1 gal (US) equalsVisual reference for how the us gallon relates to other volume units. Each row links to the full converter for that pair.
When Is the US Gallon Used?
- US fuel pricing and consumption
- US paint, oil and cleaning-product packaging
- US beverage containers (1-gallon jugs of milk)
US car tank ≈ 15 gallons (57 L). 1 US gallon of milk is a common grocery size (3.79 L). US paint often sold by the gallon.
Tips for Using the US Gallon
- 1 US gallon = 3.785 L = 128 US fluid ounces = 4 quarts.
- Converting mpg (US) to L/100 km: 235.215 / mpg = L/100 km.
- The US gallon is based on the old English Queen Anne wine gallon (1707).
Common Mistakes
- Using UK gallons on a US fuel-economy figure — 30 mpg (US) = 36 mpg (UK).
- Confusing US gallon (3.79 L) with UK gallon (4.55 L) — 20% difference.
- Using "gallon" without qualifier in cross-Atlantic commerce.