Here are the USDA guidelines: To prepare, once potatoes are cooked and mixture has mayonnaise added then “cool to 70º F in 2 hrs or less and then to 41°F in 4 hrs or less.”  Note, the USDA recommends that “if the potato salad was held in excess of 41°F for over two hours, then discard.”

A couple of things to consider… Did the potato salad get made up and then refrigerated right away and you just have some leftover?  If this is the case then it should easily last 3-4 days.  Was the potato salad used at a picnic and then placed back in the refrigerator?  Then probably no more than the next day, if that.  I usually don’t recommend saving the potato salad after it has sat out in the heat at all.

The potatoes should be fine; it’s the other ingredients you need to think about.  Are eggs part of the salad?  Less shelf life.  Was the mayo homemade? If so, homemade mayo does not last as long as commercial mayonnaise, which has pasteurized eggs and is prepared in very sterile facilities with preservatives such as salt.

Don’t save the potato salad too long, it’s not that expensive to replace.

Learn more about All Things Potato Salads here!