Volume Converter

Use this free volume converter to instantly convert between gallons, liters, cups, fluid ounces, milliliters, quarts, and pints. Enter any value and all units update automatically.

How to use this Volume Converter

Enter a value in any field and all other units update automatically. Type a volume in gallons to instantly see the equivalent in quarts, pints, cups, fluid ounces, liters, and milliliters. Type in any field and all others convert at the same time. This converter covers both US customary volume units and metric units, making it useful for cooking, automotive fluids, and liquid purchases.

Frequently asked questions

Q: How many cups are in a gallon?
A: There are 16 cups in one US gallon. The breakdown is: 1 gallon = 4 quarts = 8 pints = 16 cups = 128 fluid ounces. A helpful way to remember: think of a gallon as a large container with 4 quarts, each quart holding 2 pints, each pint holding 2 cups.

Q: How many milliliters are in a cup?
A: One US cup equals approximately 236.6 milliliters. One fluid ounce equals approximately 29.57 milliliters. These conversions are important for cooking when following recipes that use metric measurements — a 250ml serving size in a metric recipe is slightly more than one US cup.

Q: What is the difference between a fluid ounce and a regular ounce?
A: A fluid ounce measures volume (liquid capacity), while a regular ounce measures weight (mass). They are completely different units that happen to share the same name. One fluid ounce of water weighs approximately one ounce by weight, but this relationship only holds for water — not for oil, honey, or other liquids.

Q: Is a US gallon the same as a UK gallon?
A: No — a US gallon equals approximately 3.785 liters. A UK (imperial) gallon equals approximately 4.546 liters. The UK gallon is about 20% larger than the US gallon. This matters when comparing fuel economy between American and British vehicles.

Q: How do I convert liters to gallons for fuel purchases?
A: Divide the number of liters by 3.785 to get US gallons. For example, filling up with 50 liters equals 50 ÷ 3.785 = 13.2 US gallons. When traveling internationally, this converter helps estimate fuel costs and understand fuel economy ratings expressed in liters per 100 kilometers.