Gallon Calculator

How to Use the Gallon Calculator

Our gallon calculator makes it easy to convert between gallons and other volume units including liters, cups, quarts, pints, fluid ounces, cubic feet, and cubic inches. Simply enter the number of gallons and select the gallon type (US or UK), and all conversions update instantly.

You can also switch to the Water Weight mode to see how much a given volume of water weighs in pounds and kilograms. This is helpful for aquarium owners, pool maintenance, cooking, and scientific applications.

Gallon Conversion Formulas

1 US gallon = 3.785 liters = 128 fl oz = 16 cups = 8 pints = 4 quarts

1 UK gallon = 4.546 liters = 160 fl oz = 16 cups = 8 pints = 4 quarts

1 US dry gallon = 4.405 liters

To convert gallons to liters, multiply by 3.785 (US) or 4.546 (UK). To convert gallons to cubic feet, multiply by 0.13368 (US) or 0.16054 (UK).

Types of Gallons

The US liquid gallon is the most commonly used gallon in the United States and is equal to 231 cubic inches or approximately 3.785 liters. The UK (Imperial) gallon is larger at 4.546 liters and is used in the United Kingdom and some Commonwealth countries. The US dry gallon (4.405 liters) is used for measuring dry goods such as grains.

Water Weight Conversions

One US gallon of water at room temperature weighs approximately 8.345 pounds (3.785 kg). This makes the gallon calculator useful for estimating the weight of water in aquariums, pools, and water storage tanks. For example, a 55-gallon drum of water weighs approximately 459 pounds.