Imperial gallons to US fluid ounces Converter
Convert Imperial gallons (imp gal) to US fluid ounces (fl oz) instantly, or use the conversion table below to look up common values.
Imperial gallons to US fluid ounces conversion table
| Imperial gallons (imp gal) | US fluid ounces (fl oz) |
|---|---|
| 1 | 153.72159 |
| 2 | 307.443181 |
| 3 | 461.164771 |
| 4 | 614.886362 |
| 5 | 768.607952 |
| 10 | 1,537.215905 |
| 25 | 3,843.039762 |
| 50 | 7,686.079523 |
| 100 | 15,372.159046 |
How to convert Imperial gallons to US fluid ounces
1 imp gal equals 153.72159 fl oz. Use the converter above for any value, or read the table for common conversions.
fl oz = imp gal × 153.72159046462144 · imp gal = fl oz × 0.006505267067413975Multiply a imperial gallons figure by 153.72159 to get us fluid ounces, or divide it by 0.006505 to go the other way.
Worked examples
- 1 imp gal= 153.72159 fl oz
- 2 imp gal= 307.443181 fl oz
- 5 imp gal= 768.607952 fl oz
- 10 imp gal= 1,537.215905 fl oz
- 20 imp gal= 3,074.431809 fl oz
What these units are
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 fluid ounces (fl oz). A US fluid ounce is 29.5735295625 milliliters, one sixteenth of a US pint. It is used for drinks, spirits and recipe measures in the United States.
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 Imperial gallons to US fluid ounces in practice
Reading the result in us fluid ounces
A US fluid ounce is exactly 29.5735295625 milliliters, one 128th of a US gallon. It measures liquid volume and is not the same as the ounce of mass.
Beverage bottles, cocktail recipes, medicine cups, infant formula and cosmetic containers are labelled in US fluid ounces in the United States, and bar measures follow the same unit.
The US fluid ounce is exactly 1/128 of a US gallon, while the imperial fluid ounce is exactly 28.4130625 milliliters. This site uses the US fluid ounce throughout, and printed results are rounded, so a round trip can change the final digit.
The classic error is reading a fluid ounce as a weight ounce, so a 12-fluid-ounce bottle is not 12 ounces of mass. Using an imperial fluid ounce in a US recipe also differs by about four percent.
The US fluid ounce works with US cups and gallons, while milliliters and liters work with metric measures. A drink recipe that mixes them needs every quantity converted, and the fluid ounce should not be swapped for the ounce of mass.
Checking a imperial gallons to us fluid ounces 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 = 4.399385 imp gal = 676.280454 fl oz
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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