How to Reheat Mashed Potatoes (and Make Them Ahead)

To reheat mashed potatoes, add moisture and go gently. For a family-size batch, spread them in a buttered baking dish, stir in about 2 tablespoons of milk or cream per pound, dot the top with butter, cover with foil and heat at 350°F until they reach 165°F in the center, roughly 25 to 35 minutes for 2 to 3 pounds from the fridge. For a few servings, use a saucepan over low heat with the same splash of milk, stirring often, for about 5 to 8 minutes. Stir once more before serving, and add another spoonful of milk if they have tightened up.

Those times are typical starting points for fridge-cold mash, not measurements. Dish depth, how rich your mash is and how cold your fridge runs all shift them, so go by a thermometer.

This page is about mash from the fridge: last night’s leftovers, or a batch made a day ahead on purpose. If yours are frozen, our guide to freezing mashed potatoes covers thawing and the frozen reheat.

Why reheated mash goes gluey or dry

Cold mashed potatoes firm up as the starch sets and the butter hardens, so they look stiff even when nothing is wrong. Two things ruin them on the way back:

Too little moisture. Some liquid evaporates as they heat. Without a splash of milk, the top and edges dry into a crust.
Too much working. Beating hot potatoes hard, or blitzing them with a hand mixer, breaks the starch down and turns them gluey. Fold and stir. Don’t whip.

So the rules are the same for every method: add a little liquid and some fat, cover, use moderate heat, and stir gently.

How to reheat mashed potatoes, by method

Method	Liquid per pound	Heat	Rough time (from the fridge)	Best for
Oven, covered dish	About 2 tbsp milk or cream, plus butter	350°F	25–35 min for 2–3 lb	Big batches and holiday dinners
Stovetop	1–2 tbsp milk	Low	5–8 min, stirring	A family dinner
Microwave	About 1 tbsp milk	50% power	1-minute bursts, stirring	One or two plates
Slow cooker	Not for reheating	Warm	Holding only	Keeping hot mash hot

In the oven. Spread the mash no deeper than about 2 inches so the center heats before the edges dry out. Stir the milk in before it goes in, cover tightly with foil, and give it a gentle stir halfway through. For a golden top, uncover for the last 5 to 10 minutes.

On the stove. Use a heavy pot and low heat. Add the milk first, then the potatoes, and stir from the bottom every minute or so. Warm milk blends in faster than cold.

In the microwave. Cover the bowl, and use half power in short bursts with a stir between each one. Full power heats the edges long before the middle, and that is how you get the gluey edges and cold center everyone remembers.

Make-ahead mashed potatoes for a crowd

Mashed potatoes are the side that always lands last on a holiday, because they need a burner and a cook at the very moment everything else does. Making them a day ahead moves that work to the day before.

The day before: make the mash a little richer than usual, with an extra pat of butter or a spoonful of cream cheese or sour cream. Fat keeps it creamy through the fridge and the reheat. Spread it straight into the buttered baking dish you will serve it from.
Cool it fast: Illinois Extension’s leftovers guidance is to refrigerate within two hours, and a shallow dish cools far faster than a deep pot. Cover it once it is cold.
On the day: stir in the milk, dot with butter, cover, and bake at 350°F until it reaches 165°F. A big, deep dish can take 45 minutes or more, so start it before the turkey comes out to rest.
Hold it hot: move the mash to a preheated slow cooker on warm with a knob of butter on top, and stir it now and then. It holds there through a long meal.

For how many pounds of potatoes to buy, our potatoes per person chart says 1/2 lb each, and up to 3/4 lb on Thanksgiving, when mash is practically a main. It pairs with our turkey per-person chart for the rest of the shopping list.

Why not reheat them in the slow cooker?

It is the obvious holiday shortcut, and food-safety educators say no. University of Maine Cooperative Extension’s slow cooker guidance states: “A slow cooker should not be used for reheating leftovers. Use your oven, stovetop or microwave to reheat foods to 165˚F and then add to the pre-heated slow cooker.” It adds that hot foods should be held at 140°F or above. A slow cooker brings cold food up so gently that it spends a long time in the temperature range where bacteria grow fastest.

The slow cooker is still the best tool for the second half of the job. Reheat in the oven or on the stove, then hand the hot mash to the crock.

Food safety for leftover mashed potatoes

The three numbers to remember all come from Illinois Extension’s leftovers page: refrigerate within two hours of serving, use within 3 to 4 days, and reheat to at least 165°F. Mash is dense, so the center lags well behind the edges. Check the middle with an instant-read thermometer rather than trusting a steaming top.

NC State’s Safe Plates program, in its Thanksgiving leftovers advice, adds two rules that matter after a big meal:

Reheat leftovers only once. Warm what you will eat, and keep the rest cold. If there is still some left after reheating, Safe Plates says it is safest to throw it out.
Bring gravy to a rolling boil when you reheat it, before it goes over the potatoes.

FAQ

What is the best way to reheat mashed potatoes?

Covered in a 350°F oven with about 2 tablespoons of milk or cream per pound and some butter on top, stirred halfway, until the center reaches 165°F. For small amounts, a saucepan on low heat with a splash of milk works just as well.

Can you make mashed potatoes the day before?

Yes, and it is the easiest way to free up the stove on a holiday. Make them a little richer than usual, cool them quickly in a shallow dish, refrigerate, and reheat covered in the oven the next day.

How long do mashed potatoes last in the fridge?

Three to 4 days, according to Illinois Extension, as long as they went into the fridge within two hours of cooking. Freeze them if you need longer.

How do you keep mashed potatoes warm for a party?

Reheat them to 165°F first, then hold them in a preheated slow cooker on warm, stirring occasionally. Keep them at 140°F or above.

Why are my reheated mashed potatoes gluey?

They were usually over-mixed or heated too hard. Fold in a little warm milk and butter gently over low heat. Whipping or blending them again makes the glueyness worse.