How many ounces is a Canadian gallon?

A Canadian gallon contains 128 fluid ounces. This is different from the United States gallon, which contains 128 ounces.

When measuring liquid volumes, it’s important to pay attention to the type of gallon being referenced. There are two primary types of gallons used today – the imperial gallon and the US gallon.

The imperial gallon, which is used in Canada and the United Kingdom, contains 4.546 liters or 128 fluid ounces. Meanwhile, the US gallon contains 3.785 liters or 128 US fluid ounces. Since the imperial gallon is about 20% larger than the US gallon, anything measured in imperial gallons will be equivalent to around 1.2 times that amount in US gallons.

This difference can cause confusion any time measurements for recipes, fuel efficiency, fluid containers, etc. don’t specify which type of gallon is being used. To convert between the two, you need to know the exact ratio of ounces in an imperial vs US gallon.

Fluid Ounces

A fluid ounce is a unit of volume used for measuring liquids. One fluid ounce equals approximately 29.57 ml or 1.804 cubic inches. There are 128 fluid ounces in an imperial gallon and 128 US fluid ounces in a US gallon.

So the number of ounces is the same, but the actual volume of those ounces differs between the two systems. The imperial fluid ounce is about 4% larger than the US fluid ounce.

Key Differences

  • 1 imperial fluid ounce = 28.413 ml
  • 1 US fluid ounce = 29.574 ml

This may seem like a small difference, but it adds up when converting between gallons and other volume measurements.

The Canadian Gallon

Canada officially uses the imperial system of measurement. This means gallons used in Canada are imperial gallons, not US gallons.

Here are some key facts about the Canadian gallon:

  • Equals 4.546 liters
  • Contains 128 imperial fluid ounces
  • Is about 20% larger than the US gallon
  • Widely used in Canada when measuring fuel, milk, water, etc.

So a Canadian gallon, by its nature of being an imperial gallon, will always contain 128 imperial ounces. This equates to approximately 153.7 US fluid ounces.

Converting Between Gallons

To convert between Canadian (imperial) and US gallons:

  • 1 imperial gallon = 1.2 US gallons
  • 1 US gallon = 0.832674 imperial gallons

Knowing this allows you to convert any gallons-related measurement between the two systems.

Comparing Ounces

Since a Canadian gallon contains imperial fluid ounces, which are bigger than US ounces, the total ounce content is greater than in a US gallon.

Here’s a direct comparison of the ounces in each type of gallon:

Gallon Type Total Ounces
Canadian (Imperial) Gallon 128 imperial ounces
US Gallon 128 US ounces

To convert between the two:

  • 128 imperial ounces = 153.7 US ounces
  • 128 US ounces = 120.0 imperial ounces

So if you take the 128 imperial fluid ounces in a Canadian gallon, that’s equivalent to about 153.7 US fluid ounces.

Examples and Applications

Understanding how many ounces are in a Canadian gallon helps with any situation involving converting between imperial and US gallons, such as:

  • Recipes – When a recipe calls for “1 gallon of water” you need to know if it means a US or imperial gallon to get the correct amount.
  • Fuel Efficiency – Miles per imperial gallon will differ from miles per US gallon, impacting specifications and calculations.
  • Fluid Containers – A “1 gallon jug” could hold 128 imperial or US ounces depending on where it’s manufactured.
  • Shopping Online – When buying gallons or ounces of fluids from an international retailer, you need to watch which unit they use.

For example, if a Canadian recipe says to use 1 gallon of milk, you would need to use 128 imperial fluid ounces of milk, not 128 US ounces. Similarly, if you see a US product sold in “half-gallon” sizes, that’s really half an imperial gallon if you’re shopping in Canada.

Fuel Efficiency Example

A car’s fuel efficiency is advertised as 25 miles per gallon. To figure out the mileage in Canada, you would need to do:

  • US Gallons: 25 miles/gallon
  • Convert to imperial gallons: 25 x 0.832674 = 20.8 miles/imperial gallon

So the fuel mileage in Canada would be around 20.8 miles per gallon, since imperil gallons are bigger than US gallons. This impacts how much gas you would expect to use over a given distance.

Recipe Example

A recipe from a US source calls for 2 gallons of water. To adapt this recipe for Canadian use:

  • US gallons: 2 gallons
  • Convert to imperial gallons: 2 x 1.2 = 2.4 imperial gallons
  • Get total ounces: 2.4 x 128 = 307 imperial ounces

You would need 307 imperial fluid ounces of water, which is over 50 ounces more than if you used US gallons. Getting the right ounces results in the proper liquid volume for the recipe.

Other Key Differences

Beyond just gallons, there are some other key differences between imperial and US measurement systems:


  • Quarts – An imperial quart is 40 imperial ounces vs 32 US ounces for a US quart.
  • Pints – An imperial pint is 20 imperial ounces vs 16 US ounces per US pint.
  • Tablespoons – One imperial tablespoon = 17.758 ml vs 14.786 ml for a US tablespoon.


  • Miles – An imperial mile is about 1.609 kilometers while a US mile = approximately 1.609 kilometers.
  • Feet – An imperial foot is 0.3048 meters vs 0.304 meters for a US foot.

So imperial measurements will consistently be larger than the equivalent US measurements in most cases.


  • Pounds – An imperial pound is ~0.454 kilograms, but a US pound is ~0.453 kilograms.
  • Ounces – 1 imperial ounce = ~28.4 grams, while 1 US ounce = ~28.35 grams.

However, weights can be slightly different, with imperial pounds being fractionally heavier than US pounds in the common units.


A Canadian gallon always contains 128 imperial fluid ounces. This equates to approximately 153.7 US fluid ounces, or about 20% more than a standard US gallon.

Knowing the ounce difference allows you to accurately convert between imperial and US liquid measurements when dealing with gallons of any type. This is essential for recipes, fuel calculations, and any application involving fluid volumes.

While both systems use “ounces” and “gallons”, the actual amounts differ based on whether you’re using the Canadian imperial system or the US customary system. Paying attention to the units helps ensure you get the right volumes for any situation where gallons need to be converted or compared.

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