The shelf life of milk is typically five to seven days past its printed "sell by" date. According to EatByDate, whole milk has a slightly shorter shelf life, and is typically good for five days after the printed "sell by" date.
Lactose-free milk and non-fat milk reliably last seven days past their "sell by" date, and skim and reduced-fat milk last five to seven days past the "sell by" date. Milk with a lower fat content lasts a bit longer than whole milk because bacteria grow more slowly in lower-fat varieties. Milk contains no preservatives and should not be frozen. Keeping milk as cold as possible by putting it in the back of the refrigerator may help to extend its shelf life slightly.