Imperial (used in the British Empire) vs US customary. The imperial fluid gallon (4.54609 L exactly) was never historically defined in terms of another unit while the US fluid gallon was defined as 231 cubic inches (3.785411784 L exactly). A pint is defined as 1/16 of a gallon in each system, but they can't agree on how many ounces are in a pint (16 for US, 20 for imperial). Note that there are also imperial and US customary dry gallons and thus imperial and US customary dry pints...

[–] Buddahriffic@lemmy.world 2 points 5 months ago

That adds a hilarious new dimension to how shitty the Imperial system is because I had no idea that different countries would just define their own versions of the measurements.

[–] azi@mander.xyz 9 points 5 months ago (1 children)

Currently used definitions of the cup:

The US customary cup (236.6 mL) is 8 US customary fluid ounces. The US customary fluid ounce (29.6 mL) is 1/16 of a US fluid pint.

The US legal cup (240 mL) is 8 US nutritional fluid ounces. The US nutritional fluid ounce is 30 mL.

The metric cup is 250 mL

Historically used definitions of the cup:

Ths British cup (284.1 mL) is 10 imperial fluid ounces. The imperial fluid ounce (28.4 mL) is 1/20 of an imperial fluid pint

The Canadian cup (227.3 mL) is 8 imperial fluid ounces

[–] AnUnusualRelic@lemmy.world 2 points 5 months ago

Let's just forget about the whole thing.