Here’s how long your milk REALLY lasts

OK, we need to settle this once and for all: When does milk really expire? Some sources say it's good past its expiration date and others say to toss it out after just a few days of being open. We decided to get to the bottom of this conundrum.

According to Eat By Date, once opened, all milk lasts 4-7 days past its printed date, if refrigerated. If unopened, whole milk lasts 5-7 days, reduced-fat and skim milk last 7 days, and non-fat and lactose-free milk last 7-10 days past its printed date, if refrigerated. (Did you know bottled water has an expiration date? Yes, really.)

But let's clear some things up. There's a huge difference between milk date labels that say "sell by," "use by," "best if used by," and "expires on." "The phrase, "best if used by" is used to indicate quality only—even after this date, food is safe to eat. Another phrase, "expires on," is used to indicate the day that deterioration begins, after which a product may become unsafe to consume," says Lindsey Pasieka, an investigator for ConsumerSafety.org. "'Sell by' dates tell a milk seller, like a grocery store, when the product should leave the shelves–either in a customer's arms or in the trash. For many, 'use by' and 'sell by' are essentially marketing terms. These allow milk producers to tell consumers when the peak freshness of the product is. They do not indicate the exact date the milk will go bad."

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These labels vary from state to state, so it's not unusual for things to get a little confusing and for milk to be thrown out while it's still good and safe for consumption. However, it's important to note that expiration dates vary based on what kind of milk you're purchasing, how it's stored, and how it's packaged. For example, "With raw or unpasteurized milk, these spoilage rates increase, as with milk made without preservatives," says Pasieka. "Contamination can also jump-start bacteria growth, leading to sour milk." (By the way, these 8 non-food items have expiration dates, too.)

And of course, where and how you store your milk is pivotal to its freshness. According to the FDA, if milk is left unrefrigerated for more than two hours, it's considered unsafe to consume. Believe it or not, there's even a specific location in your fridge where you should be keeping your milk—and it's not on the door's shelves. According to Jen Giambroni, Director of Communications at Real California Milk, milk should be stored at 38° to 40°F in the same container it came in, and far away from the door. When milk is stored on the refrigerator door's shelves, it's being exposed to warm air each time it's opened, which encourages bacterial growth. "Also, be sure to tightly close the lid to your milk cartons," Pasieka adds. "This helps reduce accidental contamination and odors from other refrigerated products."

If you think that your milk might have prematurely expired, use your senses' best judgment. "Spoiled foods will develop an off odor, flavor or texture due to naturally occurring spoilage bacteria. If a food has developed such spoilage characteristics, it should not be eaten," says the United States Department of Agriculture. (You'll never have to worry about these 9 foods ever expiring, though.)