A US customary cup is 236.5882365 milliliters.
Cups to Imperial gallons Converter — cup to imp gal
Convert Cup (cup) to Imperial gallon (imp gal) using the exact conversion factor (1 cup = 0.0520421365 imperial gallon). See the formula, worked examples, conversion table, unit comparison, history, and common uses.
Cups to Imperial gallons converter
Converter
Volume Converter
Convert metric, US customary, imperial, cooking, dry, and industrial volume units.
Context values
Some unit families need one extra value for a physically accurate result.
An imperial gallon is exactly 4.54609 liters.
Result = input x 0.0002365882365 / 0.00454609.
Volume uses the cubic meter as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Cups to Imperial gallons
Cup and Imperial gallon appear side by side at fuel pumps and on beverage labels, since the US measures liquids in gallons while most of the world uses liters. Cup is typically associated with united States (recipes and cooking measurement), while Imperial gallon is typically associated with united Kingdom, Canada (some contexts), and other Commonwealth countries.
Formula
imperial gallons = cups × 0.0520421365393
This factor comes from each unit's defined relationship to the category's base unit: 1 cup equals 0.0002365882365 base units, and 1 imperial gallon equals 0.00454609 base units, so dividing one by the other gives the direct cup-to-imperial gallon factor of 0.0520421365393.
Simple example
1 cup × 0.05204213654 = 0.0520421365 imp gal
1 cup = 0.0520421365 imperial gallons.
Real-world example
10 cup × 0.05204213654 = 0.5204213654 imp gal
10 cups = 0.5204213654 imperial gallons.
Conversion table
| Cup (cup) | Imperial gallon (imp gal) |
|---|---|
| 1 cup | 0.0520421365 imp gal |
| 5 cup | 0.2602106827 imp gal |
| 10 cup | 0.5204213654 imp gal |
| 25 cup | 1.301053413 imp gal |
| 50 cup | 2.602106827 imp gal |
| 100 cup | 5.204213654 imp gal |
Reverse conversion: Imperial gallon to Cup
0.0520421365 imp gal × 19.21519881 = 0.9999999992 cup
0.0520421365 imperial gallons = 0.9999999992 cups.
cups = imperial gallons × 19.2151988081
For a page dedicated to this direction, see Imperial gallon to Cup.
Cup vs. Imperial gallon
| Aspect | Cup | Imperial gallon |
|---|---|---|
| Family | US customary unit (culinary) | UK/imperial customary unit |
| Typical use | US recipe and cooking measurement | UK fuel and beverage measurement (historically; UK now primarily uses liters for retail) |
| Where it's used | United States (recipes and cooking measurement) | United Kingdom, Canada (some contexts), and other Commonwealth countries |
Understanding the Cup
Cup (cup) measures volume. The US customary cup used in cooking is defined as exactly 240 milliliters (a rounded culinary standard, not the older 236.588 mL legal cup). It is classified as a US customary unit (culinary).
Where it's used: United States (recipes and cooking measurement)
Cooking cup vs. legal US cup. US recipes commonly round the cup to 240 mL for convenience, while the precise legal US cup (used to derive fluid ounces, pints, etc.) is 236.588 mL — a small but sometimes noticeable difference in precise baking.
Uses of the Cup today
- US recipe and cooking measurement
- Nutrition labeling serving sizes
- Baking, where volume-based flour/sugar measurement is still common in the US
History of the Cup
The cup as a cooking measure grew out of household and community cookbook conventions in 19th-century America, standardizing what had been ad hoc measurements ('a teacup of flour') into a fixed volume.
The US FDA uses a rounded 240 mL 'metric cup' for nutrition labeling purposes, distinct from the slightly smaller legal/customary cup (236.588 mL, exactly 1/16 of a US gallon) used elsewhere.
Historical origin. Cup was not the invention of a single named person; it developed through the process described above.
Understanding the Imperial gallon
Imperial gallon (imp gal) measures volume. The imperial gallon is defined as exactly 4.54609 liters, about 20% larger than the US gallon. It is classified as a UK/imperial customary unit.
Where it's used: United Kingdom, Canada (some contexts), and other Commonwealth countries
Imperial gallon vs. US gallon. Britain's 1824 Weights and Measures Act defined a new gallon based on 10 pounds of water, replacing the old wine gallon the US had already adopted — leaving the US (3.785 L) and imperial (4.546 L) gallons about 20% apart today.
Uses of the Imperial gallon today
- UK fuel and beverage measurement (historically; UK now primarily uses liters for retail)
- Commonwealth country liquid measurement in some contexts
History of the Imperial gallon
The imperial gallon was created by Britain's Weights and Measures Act of 1824, defined as the volume of 10 pounds of water, replacing several inconsistent older English gallon definitions (wine gallon, ale gallon, corn gallon) with one standard.
Historical origin. Imperial gallon was not the invention of a single named person; it developed through the process described above.
Cup — sources
- US FDA — Reference Amounts Customarily Consumed — Uses the 240 mL rounded cup for nutrition labeling.
Imperial gallon — sources
- UK Weights and Measures Act 1824 — Establishes the imperial gallon definition.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many imperial gallons are in 1 cup?
1 cup equals 0.0520421365 imperial gallons, using the exact defined conversion factor rather than an estimate.
How do I convert cup to imperial gallon?
Multiply the cup value by 0.05204213654. The converter above does this instantly to whatever precision you set.
How do I convert imperial gallon back to cup?
Use the reverse factor: 1 imperial gallon equals 19.21519881 cups. You can also use the swap control in the converter above to flip the direction instantly.
What is a cup?
Cup (cup) measures volume. The US customary cup used in cooking is defined as exactly 240 milliliters (a rounded culinary standard, not the older 236.588 mL legal cup). It is classified as a US customary unit (culinary).
What is a imperial gallon?
Imperial gallon (imp gal) measures volume. The imperial gallon is defined as exactly 4.54609 liters, about 20% larger than the US gallon. It is classified as a UK/imperial customary unit.
Is the cup to imperial gallon conversion exact?
Yes. The imperial gallon is defined as exactly 4.54609 liters, about 20% larger than the US gallon. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
What is the difference between cooking cup vs. legal us cup?
US recipes commonly round the cup to 240 mL for convenience, while the precise legal US cup (used to derive fluid ounces, pints, etc.) is 236.588 mL — a small but sometimes noticeable difference in precise baking.
Where is the cup still used today?
United States (recipes and cooking measurement)