You bought a ham. It’s already cooked. Technically, you could just hack off a cold slice standing over the kitchen sink at midnight and be perfectly safe. But that’s not the plan for Sunday dinner, is it? You want it juicy, warm, and glazed. The biggest mistake people make is treating a precooked ham like a raw piece of meat. If you do that, you’re basically making pork jerky.
Timing is everything.
Honestly, the "cooking" part is a bit of a misnomer because you’re actually just reheating. Most hams you buy at the grocery store, whether it’s a Smithfield, a Hormel, or a local butcher’s cure, have already been smoked or boiled to an internal temperature of at least 145°F or 150°F. Your only job is to get that chill out of the center without turning the outside into a salty desert.
How long to cook a precooked ham: The Golden Rule
The baseline you need to memorize is 10 to 12 minutes per pound. If you have a 10-pound ham, you're looking at about two hours.
Wait.
Don't just set a timer and walk away. That 10-12 minute rule only works if your oven is set to a low, gentle temperature—usually around 325°F. If you crank it up to 400°F because you’re in a rush, you’ll burn the sugar in the glaze and the meat will tighten up like a drumhead.
USDA guidelines are pretty clear on this: for a ham that was packaged in a federally inspected plant, you want to bring it to an internal temperature of 140°F. If it’s a "leftover" ham or something you didn't buy pre-packaged, you should go all the way to 165°F for safety. But for that standard spiral-sliced holiday ham? 140°F is the sweet spot.
Bone-in vs. Boneless: Why it matters
A boneless ham is basically a tight muscle mass. Heat travels through it relatively evenly, but it lacks the protection and flavor-conductivity of the bone. For a boneless ham, stick closer to that 10-minute-per-pound mark.
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Bone-in hams are trickier. The bone actually acts as a thermal conductor once it gets hot, but it takes a while to get there. Because of the bone's irregular shape, you’ll often find the meat closest to the bone stays cold while the outer edges start to dry. This is why foil is your best friend.
Wrapping the ham tightly in heavy-duty aluminum foil is non-negotiable. You’re trying to create a steam chamber. If you leave it exposed the whole time, the air in the oven will suck every drop of moisture out of those thin slices.
The Spiral-Cut Problem
Spiral-cut hams are the most popular choice for convenience, but they are also the easiest to ruin. Think about it. The meat is already sliced. You’ve just increased the surface area by about a thousand percent. Every one of those slices is an opportunity for moisture to escape.
If you’re wondering how long to cook a precooked ham that’s already sliced, you have to be even more careful. Some experts, like the folks at Cook's Illustrated, actually recommend placing the ham cut-side down in a baking pan with a little bit of water or apple cider at the bottom. Then you wrap the whole thing—pan and all—in foil. This creates a "water bath" effect that keeps the slices from curling up and turning into leather.
Why your meat thermometer is the only thing that's right
Your oven is probably lying to you. Most home ovens are off by 10 to 25 degrees. This is why "minutes per pound" is just a guess.
Take the ham out when it hits 130°F.
Yes, I said 130°F.
Carryover cooking is a real scientific phenomenon. Once you pull that big hunk of meat out of the heat, the residual energy on the surface continues to travel toward the center. If you wait until the thermometer reads 140°F in the oven, it’ll likely hit 150°F by the time you carve it. That 10-degree difference is the gap between "best ham ever" and "pass the extra gravy, please."
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Glazing: The final 15 minutes
Don't put your glaze on at the beginning. Most glazes are packed with sugar—honey, brown sugar, maple syrup, or even pineapple juice. Sugar burns. If you put it on at the start of a two-hour cook, you’ll have a blackened, bitter mess.
- Heat the ham to about 120°F (usually about 15-20 minutes before it’s done).
- Remove it from the oven and turn the heat up to 400°F.
- Unwrap the foil and brush that glaze on thick.
- Put it back in, uncovered.
- Watch it like a hawk.
You only need 10 to 15 minutes here. You’re looking for bubbles and a nice caramelized shine. Once it looks like a magazine cover, get it out of there.
Unusual Variables: Slow Cookers and Air Fryers
Can you do this in a Crock-Pot? Sure. It’s actually a great way to keep it moist because the environment is so sealed. For a small 4-6 pound ham in a slow cooker, you’re looking at 4 to 5 hours on Low. Don’t use High; it toughens the proteins.
Air fryers are the new frontier, but they’re really only good for ham steaks or very small boneless "quartet" hams. If you jam a 3-pound ham in there, the fan will blast the outside into a crisp before the middle is even lukewarm. If you must use an air fryer, wrap the ham in foil and cook at 300°F for about 30 minutes, checking the center frequently.
Real Talk on "Room Temperature"
A lot of old-school cookbooks tell you to let the meat sit on the counter for two hours before cooking to "take the chill off."
Don't do that.
The thermal mass of a 10-pound ham is huge. Two hours on the counter will only raise the internal temperature by a few degrees, but it puts the surface of the meat in the "danger zone" for bacterial growth for way too long. Take it straight from the fridge to the oven. Just account for an extra 10-15 minutes of total cook time.
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Actionable Next Steps
- Check your equipment: Find your meat thermometer now. If it’s an old analog one, calibrate it in a glass of ice water (it should read 32°F).
- Measure your pan: Make sure your roasting pan is deep enough to hold at least a cup of liquid without splashing when you move it.
- Buy heavy-duty foil: Regular foil tears too easily when you're trying to wrap a heavy, bone-in ham.
- Liquid gold: Pick your steaming liquid. Plain water works, but apple juice, ginger ale, or even a splash of bourbon adds a layer of aromatics that plain steam can’t touch.
- The Rest Period: Once the ham is out, let it sit for at least 20 minutes before carving. This lets the juices redistribute so they stay in the meat rather than flooding your cutting board.