This free converter changes US gallons (gal) to cups and back again, updating live as you type into either field. It is useful for scaling recipes, batching drinks, and reading water-cooler or jug capacities in everyday cup measures.
How it works
US customary volume units nest neatly in powers of two: 1 gallon = 4 quarts, 1 quart = 2 pints, and 1 pint = 2 cups. That gives a fixed, exact relationship of 16 US cups per gallon:
cups = gallons × 16 (and gallons = cups ÷ 16)
Type in the gallons field and it multiplies by 16; type in the cups field and it divides by 16. Results display up to 8 significant figures.
Reference table
| US gallons | Cups | Practical context |
|---|---|---|
| 0.125 gal | 2 cups | A standard pint jar |
| 0.25 gal | 4 cups | One US quart |
| 0.5 gal | 8 cups | Half-gallon juice carton |
| 1 gal | 16 cups | Standard milk jug |
| 2 gal | 32 cups | Large lemonade batch |
| 5 gal | 80 cups | Water-cooler jug |
Common uses
Scaling recipes. Most large batch recipes for things like sangria, iced tea, or lemonade are written in gallons, but your measuring cups are in… cups. A one-gallon recipe needs 16 cups of liquid total.
Cooking and baking. When a restaurant recipe calls for 0.75 gal of stock, that is 12 cups — easy to measure in three four-cup pitchers.
5-gallon water cooler bottles. These hold 80 cups, or roughly 40 servings of two cups each — a common calculation for event planning.
US cups vs metric cups — an important distinction
This converter uses the US customary cup, which is exactly 236.588 mL. A metric cup (used in Australia, Canada in some contexts, and metric recipes) is 250 mL — about 5.7% larger. If your recipe is from an Australian cookbook, 1 cup there is slightly more than 1 US cup. The difference matters for precision baking: 4 metric cups of flour is about 20 mL more than 4 US cups, which can affect the dough texture.
UK recipes that predate metrication sometimes reference an older “imperial cup” of 284 mL (half an imperial pint). This is rarer in modern recipes but worth knowing if you are cooking from vintage British sources.
Quick mental maths shortcut
When you do not have a calculator handy, remember the hierarchy: a gallon is 4 quarts, a quart is 2 pints, and a pint is 2 cups. So multiply gallons by 4, then by 2, then by 2 again — or simply by 16. For half-gallon quantities (common for orange juice cartons), the answer is always 8 cups. For quart quantities (common for stock and broth), it is always 4 cups.
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