Generally, macaroni salad can last for 3 to 5 days in the fridge if stored properly. This means keeping it in an airtight container at a consistent refrigerator temperature of 40°F (4°C) or below. Think of it like keeping your favorite snack fresh - you want to keep it cool, dry, and away from any pesky bacteria.
But, just like how your favorite pair of jeans can go from comfy to so-last-season, macaroni salad can go from delicious to downright disgusting if not stored correctly. For example, if you leave it out at room temperature for too long, bacteria like Staphylococcus aureus can start to grow, making you and your stomach very unhappy.
