Whether leftovers last a day or a year depends on the food itself and whether you plan to store the leftovers in the refrigerator or the freezer. The answer also depends on whether the leftovers contain meat, poultry, eggs, dairy products or vegetables. That said, some rules of thumb and common sense apply to most leftovers.

Cooked meats and chicken, including combination dishes such as chicken pot pie, last from three to five days in the fridge and from two to six months in the freezer. As with all leftovers, wrap the foods well in plastic or keep them in a covered glass dish.

Most casseroles, soups and stews with combinations of meat, poultry and vegetables last from three to four days in the refrigerator and two to three months in the freezer. You can also refrigerate macaroni and cheese and quiche for three to four days, but these dishes don't freeze as well, with macaroni and cheese lasting one to two months and quiche lasting two to three months.

Creamy, mayonnaise-based salads, like tuna salad, egg salad or pasta salad, stay safe for three to five days in the refrigerator, but some of their ingredients may lose their crispness. Tomatoes may become runny and parsley may become wilted. Green salads don't hold up nearly as long, lasting only one day before the lettuce turns soft and can't be frozen at all.

A few stray green beans, a stalk of broccoli, diced beets, carrots or most other leftover vegetables stay safe and retain their quality or three to five days in the fridge and up to 12 months in the freezer. Avoid freezing certain vegetables, such as mushrooms, which turn mushy or even slimy after freezing. Within the three-to-five day period, chop vegetable leftovers up to toss in a green salad or a minestrone soup before they go bad. Or, puree them in your breakfast smoothie for a nutritional boost.

Leftover cream soups, custards and dips made with sour cream last from three to four days in the refrigerator, but they do not freeze well. In the freezer, the water in the cheese or milk separates from the whey and turns to ice crystals. When you thaw the dip or soup, the water doesn't reincorporate with the whey, and the texture of the food turns grainy or crumbly instead of remaining creamy and smooth.

Leftovers that you place in the freezer stay safe indefinitely as long as the freezer remains at or below 0 degrees Fahrenheit. But the quality of some foods can suffer, with freezer burn or ice crystals forming after a few months. The freezer damage changes the texture and taste of your leftovers. Extend the life of any leftover food by wrapping it well in freezer-grade plastic or aluminum foil before placing it in the freezer.