How to Convert Cups to Gallons
The conversion between cups and gallons is straightforward in both the US and UK measurement systems. In the US system, one cup equals exactly 8 US fluid ounces, or 236.588 mL. There are 16 cups in a US gallon, so the formula is:
Gallons = Cups ÷ 16
To go the other way, from gallons to cups:
Cups = Gallons × 16
For example, 4 cups divided by 16 equals 0.25 gallons (one quarter of a gallon, also called a quart). And 2 gallons multiplied by 16 equals 32 cups.
US vs UK Measurement Systems
The US and UK use different definitions for cups and gallons, so it is important to know which system applies to your recipe or task.
| Measurement | US customary | UK imperial |
|---|
| 1 cup | 236.588 mL | 284.131 mL |
| 1 gallon | 3,785.41 mL (3.785 L) | 4,546.09 mL (4.546 L) |
| Cups per gallon | 16 | 16 |
| Fluid ounces per cup | 8 US fl oz | 10 UK fl oz |
| Pints per gallon | 8 | 8 |
Both systems have 16 cups per gallon because the ratio of cup to gallon is the same in each system (both divide the gallon into 8 pints and each pint into 2 cups). However, because the underlying volumes differ, a UK cup holds more than a US cup, and a UK gallon holds more than a US gallon.
Most recipes from the United States use US cups. Recipes from the United Kingdom, Australia, Canada, and New Zealand typically use metric measures (mL and L), though older recipes may reference imperial cups.
Common Cup Conversions
| Cups | US Gallons | US Litres | Common name |
|---|
| 1 | 0.0625 | 0.237 | 1 cup |
| 2 | 0.125 | 0.473 | 1 US pint |
| 4 | 0.25 | 0.946 | 1 US quart |
| 8 | 0.5 | 1.893 | Half gallon |
| 16 | 1 | 3.785 | 1 US gallon |
| 32 | 2 | 7.571 | 2 US gallons |
| 64 | 4 | 15.142 | 4 US gallons |
Worked Example
You need to convert 16 cups to gallons for a US recipe.
Gallons = 16 ÷ 16 = 1 gallon
In litres: 16 × 236.588 mL = 3,785.41 mL = 3.785 litres
This matches the default result shown in the calculator above.
Related Calculators
Sources and method: US cup defined as 8 US fluid ounces = 236.5882365 mL (NIST Handbook 44). US gallon = 231 cubic inches = 3,785.411784 mL. UK imperial cup = 10 UK fluid ounces = 284.130625 mL. UK gallon = 4,546.09 mL (Weights and Measures Act 1985). Ratio: 16 cups per gallon in both systems.
This converter uses exact definitions for US customary and UK imperial units. For cooking purposes, small rounding differences between measurement systems are generally insignificant. Always check which cup size your recipe uses before converting.
