Cup of Babylon

I recently got into an argument over how big a cup is. I’d thought that measurement came in only two sizes, Imperial and Metric, so I hit up Wikipedia.

1 U.S. legal cup 240mL
1 U.S. customary cup 236.5882365mL
1 Metric cup 250mL
1 Imperial cup 284mL
1 Canadian customary cup 227.3045mL
1 cup in some Latin American countries 200mL
1 contemporary Japanese cup 200mL
1 historic Japanese cup 180.3906836mL

… This is why we cannot have nice things.