Depends which definition of "cup" you use.
The US "legal" cup is 240 ml, so 1080ml is 1080/240 = 4.5 cups.
The US "customary" cup is 236.5882365 ml so 1080 ml is 1080/236.5882365 = 4.56489... cups
The "metric" cup is 250 ml so 1080 ml is 1080/250 = 4.32 cups.
Take your pick!
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