Buy just enough.
A gallon of milk may be cheaper per ounce, but if you don't use it all before it goes bad, you're pouring money down the drain. You'll save in the long run by buying half-gallons or quarts if that's all your family will use. A good rule of thumb is to buy only as much milk at a time as you think you'll use in a week.
Keep it cold.
For each 18-degree increase in temperature, the spoilage rate of milk doubles. If it takes 45 minutes to get milk from the dairy case to your home, milk may already have reached 60 degrees on a warm spring or summer day, so buy an inexpensive (and eco-friendly) reusable insulated bag or use a small cooler and ice pack for your milk's trip home. If stored properly, milk will keep up to five days beyond the sell-by date.
Milk labeled protein-fortified contains added dried milk proteins, which increase protein content by 2 to 3 g per cup and calcium content from 30 percent to 35 percent of the Daily Value. This type of milk is also more expensive―as much as twice the price―and not worth it.
With organic, it pays to shop around.
In her book What to Eat, Marion Nestle writes that "organic dairy foods are the fastest-growing segment of that industry….[They] brought in $1.4 billion in sales in 2003, but that figure was 20 percent higher than in the previous year." With so many new organic options, prices can vary widely. To save, look for organic store brands (the milk is likely produced by a major organic producer like Aurora or Horizon). Also, shop around―one store’s organic line may be less than another’s, or you may find a good deal from a small local dairy.