US gallons to Imperial gallons Converter
Convert US gallons (gal) to Imperial gallons (imp gal) instantly, or use the conversion table below to look up common values.
US gallons to Imperial gallons conversion table
| US gallons (gal) | Imperial gallons (imp gal) |
|---|---|
| 1 | 0.832674 |
| 2 | 1.665348 |
| 3 | 2.498023 |
| 4 | 3.330697 |
| 5 | 4.163371 |
| 10 | 8.326742 |
| 25 | 20.816855 |
| 50 | 41.633709 |
| 100 | 83.267418 |
How to convert US gallons to Imperial gallons
1 gal equals 0.832674 imp gal. Use the converter above for any value, or read the table for common conversions.
imp gal = gal × 0.8326741846289888 · gal = imp gal × 1.200949925504855Multiply a us gallons figure by 0.832674 to get imperial gallons, or divide it by 1.20095 to go the other way.
Worked examples
- 1 gal= 0.832674 imp gal
- 2 gal= 1.665348 imp gal
- 5 gal= 4.163371 imp gal
- 10 gal= 8.326742 imp gal
- 20 gal= 16.653484 imp gal
What these units are
US gallons (gal). A US gallon is 3.785411784 liters, defined as 231 cubic inches. It is the standard liquid and fuel unit in the United States, and is about 20% smaller than an imperial gallon.
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 gallons to Imperial gallons in practice
Working in us gallons
A US gallon is exactly 3.785411784 liters, or 231 cubic inches, and it divides into four quarts, eight pints or 128 US fluid ounces. It is a defined liquid volume and not a unit of mass.
Fuel at filling stations, paint, milk, water and agricultural sprays are sold by the US gallon in the United States and in some export markets. Larger tanks and drums are also rated in gallons.
The site uses the US gallon of exactly 3.785411784 liters; the imperial gallon is exactly 4.54609 liters and is roughly a fifth larger. Display rounding can move the final digit of a gallon to liter conversion taken both ways.
The frequent mistake is applying the imperial gallon to a US figure or the reverse, which misstates fuel or tank volume by around a fifth. A gallon also measures volume, while a gallon of a specific liquid has a mass.
The US gallon belongs with quarts, pints and fluid ounces, while the imperial gallon and the liter sit on other scales. Fuel is sold by the gallon in some markets and by the liter in others, so a consumption figure must be converted first.
Checking a us gallons 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 = 5.283441 gal = 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
Related conversions
More volume conversions you can convert instantly.