Turn the power down to about 70 percent, cover the dish loosely, and stop halfway through to stir or rotate it. A microwave set to full power drives the outside of food hot long before heat has time to reach the center, so the fix isn't more time — it's giving the center a chance to catch up before the surface overcooks.
Why the edges finish before the middle does
A microwave heats by flipping an electric field back and forth about 2.45 billion times a second. Water molecules are polar, so they twist to follow that field, and the friction from all that twisting is the heat you feel. But the field only reaches about an inch into food before most of its energy is absorbed.
Past that depth, there's no more field to twist molecules with. Heat has to travel the old way, by conduction, one molecule handing warmth to the next — the same slow process an oven relies on. The outer inch heats directly and fast. The center is stuck waiting on conduction. Leave the power at 100 percent and the outside is scalding well before that wait is over.
Why cutting the power helps more than cutting the time
At full power the surface never gets a break — it keeps absorbing energy nonstop and racing further ahead of the interior. Dial the power down and the microwave doesn't actually run weaker. It cycles the magnetron on and off in short bursts, so the outer layer gets pauses to bleed heat inward instead of just piling more on top of what's already there.
The total energy delivered ends up about the same. It just arrives spread over more time, which is exactly what lets the center close the gap instead of falling further behind.
Why covering the dish keeps it from drying out
Water at the surface is the first thing a microwave heats, and left uncovered, it evaporates as fast as it forms. A loosely fitted lid or a vented sheet of plastic wrap traps that rising steam right above the food, which raises the humidity around it until evaporation slows to roughly match how fast new steam is arriving.
That's what actually saves a reheated slice of pizza from going leathery — a wetter environment for the two minutes it's in there, not a shorter cook time. Rice or pasta that came out of the fridge with no moisture to spare benefits from a spoonful of water added before the lid goes on, for the same reason.
Why the dish needs to move, even if the microwave doesn't
Microwaves bounce around inside the cavity and interfere with each other, building a pattern of energy peaks and near-dead zones only a few centimeters apart. A dish that sits still cooks unevenly no matter how long it runs, because the same spot on the plate keeps landing in the same dead zone every cycle.
A turntable moves food continuously through both the peaks and the gaps, which is why pulling it out to fit a larger dish is nearly always the wrong trade. No turntable, or a plate too wide to spin? Give it a quarter-turn by hand every thirty seconds instead.
Checking it's actually ready
Steam should rise steadily from the middle of the dish, not just curl off one corner — a single wisp usually means one spot got hot and the rest didn't. Press into the center, or cut it open. It should give the same way the edges do, with no stiffer, cooler core underneath. Reheated meat and sauce tend to smell sharper once they're genuinely hot; something that still smells the way it did cold isn't done, whatever the timer says.
This is more than a texture question. Because a microwave heats unevenly by nature, a plate can read hot at the rim while a pocket near the center never clears 140°F (60°C) — well within the range bacteria tolerate. Stir anything stirrable and check more than one spot on anything that can't be stirred before calling it reheated. For food that started as raw meat or poultry, the center needs to reach 165°F (74°C).