The US cup
The US legal cup, as used in nutrition labels, equals exactly 240 mL; the US customary cup, used in recipes, equals 236.5882365 mL (half a US liquid pint, or 8 US fluid ounces). Convertitive uses the customary value, which matches how most US cookbooks specify quantities. UK and Australian metric cups are 250 mL — yet another small but consequential difference.