Subject: British Gallon

Name: Shawn

Who is asking: Other Level: Middle

Do we use British or American gallons in Canada?

Hi Shawn,

Part of the motivation for Canada switching from the "British" units to metric units was the confusion caused by liquid measure. The word "gallon" used to have two different meanings. Although both of these gallon values are approximately 4 litres, the difference is significant. Today nobody uses the British Imperial gallon.

In Canada we formerly used

The British imperial gallon = 277.42 cubic inches
= 1.201 US gallons
= 4.546 litres
= 160 British fluid ounces

In the US they still use

The US gallon = 231 cubic inches
= 3.785 litres
= .833 British gallon
= 128 US fluid ounces.

This size difference explains why visitors to Canada from the US believed that there was something special in Canadian gasoline -- when they started using Canadain gas their cars suddenly got 20% more miles to the gallon.

Note that even though the Canadian (= British Imperial) gallon was bigger than the US gallon, things are flipped around for fluid ounces: the Canadian (= British Imperial) fluid ounce was SMALLER than the US fluid ounce (1.734 cu in versus 1.805 cu in).

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