US cups to Imperial gallons Converter
Convert US cups (cup) to Imperial gallons (imp gal) instantly, or use the conversion table below to look up common values.
US cups to Imperial gallons conversion table
| US cups (cup) | Imperial gallons (imp gal) |
|---|---|
| 1 | 0.052042 |
| 2 | 0.104084 |
| 3 | 0.156126 |
| 4 | 0.208169 |
| 5 | 0.260211 |
| 10 | 0.520421 |
| 25 | 1.301053 |
| 50 | 2.602107 |
| 100 | 5.204214 |
How to convert US cups to Imperial gallons
1 cup equals 0.052042 imp gal. Use the converter above for any value, or read the table for common conversions.
imp gal = cup × 0.0520421365393118 · cup = imp gal × 19.21519880807768Multiply a us cups figure by 0.052042 to get imperial gallons, or divide it by 19.215199 to go the other way.
Worked examples
- 1 cup= 0.052042 imp gal
- 2 cup= 0.104084 imp gal
- 5 cup= 0.260211 imp gal
- 10 cup= 0.520421 imp gal
- 20 cup= 1.040843 imp gal
What these units are
US cups (cup). A US cup is 236.5882365 milliliters, or 8 US fluid ounces. It is the standard measure in American recipes; metric and Australian cups are 250 milliliters, so a recipe's cup depends on where it was written.
Imperial gallons (imp gal). An imperial gallon is 4.54609 liters, about 20% more than a US gallon. It is the traditional UK and Commonwealth liquid unit, now largely replaced by liters.
US and imperial units are kept separate because they are genuinely different sizes. Confirm which system a source means before trusting a converted figure.
Converting US cups to Imperial gallons in practice
Working in us cups
A US cup is exactly 236.5882365 milliliters, one sixteenth of a US gallon and eight US fluid ounces. It is a recipe measure rather than a general liquid unit.
It appears in American and adapted recipe books, baking charts, measuring cup sets and some packaged food directions. Outside cooking it is rarely a legal or trade unit.
The US cup is exactly eight US fluid ounces, so cup to milliliter conversions are exact at 236.5882365. Results are rounded for display, which can shift the last digit on a return conversion.
The trap is the US legal cup of 240 milliliters used on nutrition labels, and the separate metric cup of 250 milliliters; neither matches this unit. Recipe cups are also level, not heaped.
The US cup belongs with US fluid ounces and pints, while milliliters and liters belong to the metric recipe. A metric jug marked in milliliters will not match a cup measure exactly, so a recipe converted cup by cup accumulates a small error each step.
Checking a us cups to imperial gallons conversion
The metric volume units are a clean decimal chain around the liter, so liters to milliliters is a shift of three places and cubic meters to liters is a shift of three the other way. Those pairs a reader can do without a converter.
Every pair that names a US or imperial liquid unit has to go through the definition first, because three of these units differ from a metric unit by amounts too large to round away: a liter is not a quart, a gallon is 3.785411784 liters in the US system and 4.54609 in the imperial one, and a US fluid ounce is not an imperial fluid ounce.
When checking a volume conversion, convert into liters and out again, or measure the container. The mistake that survives every other check is reading a US measure as the imperial unit of the same name, which changes a recipe, a fuel figure or a tank size by about a fifth.
Tanzania reference points
Real quantities, converted into the units on this page.
The 20-litre bucket or canister used to carry water in Tanzania
20 L = 84.535057 cup = 4.399385 imp gal
WaterAid puts the minimum daily water need per person at 20 litres, so one container is roughly one person's daily requirement.
Source: IPS News — water access in Tanzania, citing WaterAid · verified 2026-09-14
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