How To Convert Gallon to Imperial Gallon
Formula: imperial gallons = gallons × 0.83267384
Example: Convert 7 gal to imp gal.
7 × 0.83267384 = 5.82871688 imp gal
To convert by hand, you only need one number, 0.83267384. Multiply your gallons by this value. The result is in imperial gallons. This works for whole numbers and decimals.
Quick Answer
1 gal = 0.83267384 imp gal
- 2 gal = 1.66534768 imp gal
- 5 gal = 4.16336920 imp gal
- 10 gal = 8.32673840 imp gal
Conversion Formula
Imperial gallons (imp gal) = Gallons (gal) × 0.83267384
This means the imperial gallon is larger than the US gallon. So when you convert from gallons to imperial gallons, the number gets smaller. For every 1 gal you have, it equals 0.83267384 imp gal.
- Write down your value in gal.
- Multiply it by 0.83267384.
- The answer is in imp gal.
Gallon
A gallon (gal) is a unit of volume most often used in the United States for liquids. In this page, “gallon” means the US liquid gallon.
The US gallon comes from older English volume measures and was standardized in the US over time. Today it is defined exactly as 231 cubic inches, which connects it to inch based measurements.
Symbol: gal
- Measuring fuel at gas stations in the US
- Milk, juice, and water containers
- Paint and chemical containers
- Home brewing and cooking in large batches
- Water usage and irrigation estimates
Imperial Gallon
An imperial gallon (imp gal) is a unit of volume used in the UK and in some Commonwealth contexts. It is larger than the US gallon.
The imperial gallon was set by the UK Weights and Measures Act of 1824. It was designed around a defined volume related to water, and it is now fixed as exactly 4.54609 liters.
Symbol: imp gal
- Fuel economy in miles per imperial gallon (UK mpg)
- Older UK and Commonwealth recipes and manuals
- Some aviation and marine references
- Historical trade and engineering documents
- Classic car and motorcycle specifications
Is this Conversion of Gallon To Imperial Gallon Accurate?
Yes. This conversion uses internationally accepted definitions. The US liquid gallon is defined exactly as 231 cubic inches. The inch is defined exactly as 2.54 cm, and this links the US gallon to the liter with high precision. The imperial gallon is defined exactly as 4.54609 liters. Using these fixed definitions gives a stable ratio of 1 gal = 0.83267384 imp gal, which is consistent with engineering references and measurement standards. For more details, see our accuracy standards.
Real Life Examples
Here are practical cases where people often need gallons to imperial gallons.
- US road trip planning in the UK: If a rental quote mentions 12 gal of fuel capacity, that is 12 × 0.83267384 = 9.99208608 imp gal.
- Comparing fuel economy: If you track 10 gal used in the US system, that equals 8.32673840 imp gal, which helps compare with UK mpg based logs.
- Shipping liquids internationally: A container filled with 50 gal is 50 × 0.83267384 = 41.63369200 imp gal for an imperial based document.
- Workshop fluid order: A mechanic ordering 5 gal of coolant is handling 4.16336920 imp gal in imperial terms.
- Small tank conversion: A 2 gal jug equals 1.66534768 imp gal, useful when a manual lists capacities in imperial gallons.
- Water storage estimate: A 100 gal holding tank equals 83.26738400 imp gal, for comparing with an imperial rated tank.
- Event beverages: If you plan 15 gal of drink mix, that is 12.49010760 imp gal for an imperial measuring setup.
Quick Tips
- Imperial gallons are bigger, so the converted number will be smaller.
- For a quick estimate, multiply gallons by about 0.83.
- For better accuracy, use 0.83267384 in your calculator.
- If you need to go the other way, imperial gallons to gallons, divide by 0.83267384.
- Always confirm which “gallon” is meant, US gal and imp gal are not the same.
- Keep the unit labels in your notes, gal vs imp gal prevents mistakes.