Pour off about one cup of milk from a full gallon jug to allow room for expansion (milk expands as it freezes). If using rigid containers, leave 1 inch of headspace.
Milk can be frozen directly in its original plastic jug (not glass bottles — they can crack). Make sure to remove some milk first to create expansion room. Lay the jug on its side for the first few hours if needed to distribute the expansion evenly.
For smaller portions, pour milk into ice cube trays or small freezer bags. Milk ice cubes are convenient for adding to smoothies, coffee (iced coffee that doesn't dilute), and small recipe needs.
1 to 3 months.
Thaw in the refrigerator — a full gallon takes 2 to 3 days. Shake well before using to reincorporate separated fat. Thawed milk is best used in cooking and baking rather than drinking, as the texture may be slightly different.