How long (how many days) does a half gallon of milk stay good after you open it?!

Best Answer - Chosen by Voters

It doesn't matter what kind of milk. Generally, the date on the milk will be close to when it goes back (within 5 days either way). If you pour a glass of milk and are suspicious of it, look at the top. If it's bad, there will be star-like things floating on the top of the milk. If you don't see the stars, smell it. If it smells sour, it's bad. If it doesn't smell or just smells like milk, probably good. Still suspicious? Take a sip. If it doesn't taste right, spit it out and toss the milk.

If it is opened after the Sell by date it is still good for about a week after opening.

It really is good until the date printed on it.

A week or two