Preparing a holiday meal or a Sunday dinner often centers around a beautiful, glazed ham. Because most hams purchased at the grocery store are already cured and fully cooked, the process is less about "cooking" and more about "reheating." However, this distinction is where many home cooks run into trouble. If you heat it too long, you end up with a dry, salty mess; if you don’t heat it long enough, the center remains unpleasantly cold. Understanding how long to cook a precooked ham is the secret to serving a juicy, flavorful centerpiece that tastes like it was prepared by a professional chef.
Understanding Your Precooked Ham Options
Before you can determine the timing, you need to know exactly what kind of ham you have sitting in your refrigerator. Not all precooked hams are created equal, and their structure dictates the best heating method.
The most common variety is the spiral-sliced ham. These are incredibly popular because the hard work of carving has already been done for you. However, because the meat is already sliced down to the bone, it is much more susceptible to drying out. These hams require a lower temperature and a shorter duration in the oven.
Whole or half hams that are not sliced offer more protection for the internal meat. These take a bit longer to heat through but are generally more forgiving if you accidentally leave them in the oven for an extra ten minutes. You might also encounter canned hams or boneless ham roasts, which are dense and uniform, requiring consistent heat to reach the center without scorching the exterior.
The Standard Rule for Oven Heating
When using a conventional oven, the general rule of thumb for how long to cook a precooked ham is 10 to 15 minutes per pound. This timing is based on an oven temperature of 325 degrees Fahrenheit. At this moderate heat, the ham has enough time to warm through to the bone without the exterior becoming tough or leathery.
For a standard 8 to 10-pound ham, you should plan for a total time of about 2 to 2.5 hours. If you are working with a smaller boneless ham, perhaps weighing only 3 or 4 pounds, it may be ready in as little as 45 minutes to an hour.
The goal is to reach an internal temperature of 140 degrees Fahrenheit. This is the sweet spot where the ham is hot enough to be delicious but has not yet begun to lose its essential moisture. Using a meat thermometer is the only way to be absolutely certain of your timing, as oven calibrations and ham shapes vary significantly.
How to Prepare Your Ham for the Oven
To ensure the timing remains accurate, you must prepare the ham correctly before it even enters the oven. Start by taking the ham out of the refrigerator about 30 to 60 minutes before you plan to cook it. Taking the chill off the meat helps it heat more evenly.
Place the ham in a heavy roasting pan. For a spiral ham, it is best to place it cut-side down. This protects the slices from direct exposure to the air, which prevents them from curling and drying out. Adding a small amount of liquid to the bottom of the pan—such as water, apple juice, or even a splash of white wine—creates a moist environment.
Wrapping the ham tightly in heavy-duty aluminum foil is the most critical step in managing your cooking time. The foil traps the steam generated by the liquid in the pan, essentially "braising" the ham as it reheats. If the foil is loose, steam escapes, and you will likely need to increase the cooking time, which increases the risk of dryness.
Adjusting Time for Glazing
Most people want that signature sticky, sweet crust on their ham. If your ham comes with a glaze packet or if you are making your own from brown sugar, honey, and Dijon mustard, you need to account for this in your schedule.
You should not apply the glaze at the beginning of the process. Because glazes are high in sugar, they will burn if left in the oven for the full two hours. Instead, wait until the ham is about 20 to 30 minutes away from being finished.
At this point, carefully remove the ham from the oven and increase the oven temperature to 400 degrees Fahrenheit. Remove the foil, brush the glaze liberally over the entire surface, and return it to the oven uncovered. This final blast of heat carmelizes the sugars quickly. This adds about 15 to 20 minutes to your total time, but it is an essential step for that classic holiday look.
Alternative Methods and Their Timings
While the oven is the traditional choice, other appliances can change how long it takes to cook a precooked ham.
If you are using a slow cooker, the process is much slower but very hands-off. A small to medium-sized ham will take about 4 to 6 hours on the "low" setting. This is an excellent method for keeping the meat moist, as the sealed environment of the slow cooker prevents any evaporation.
For those in a hurry, an Instant Pot or pressure cooker can cut the time down significantly. Generally, you look at about 2 to 3 minutes of high pressure per pound, followed by a natural pressure release. However, this is usually reserved for smaller, boneless cuts that can actually fit inside the pressure cooker insert.
If you are using an electric roaster oven, follow the same guidelines as a standard oven: 325 degrees Fahrenheit for 10 to 15 minutes per pound. Roaster ovens are often more efficient at holding in moisture, so check the temperature on the earlier side of the window.
Safety and Temperature Guidelines
The USDA notes that while precooked hams are technically safe to eat cold right out of the package, reheating them improves the texture and flavor. However, if the ham was packaged in a plant that is not USDA-inspected, or if it is a "ham leftover," it must be heated to an internal temperature of 165 degrees Fahrenheit to ensure food safety.
For a standard, vacuum-sealed ham from a reputable grocer, 140 degrees Fahrenheit is the standard for quality. If you go much higher than 150 degrees Fahrenheit, the muscle fibers begin to tighten and squeeze out the juices, resulting in a "woody" or rubbery texture.
Resting the Ham
Once the thermometer hits your target temperature, your job isn’t quite done. You must allow the ham to rest. Take it out of the oven, tent it loosely with foil, and let it sit on the counter for at least 15 to 20 minutes.
During this time, the internal juices redistribute themselves. If you cut into the ham immediately, those juices will run out onto the cutting board, leaving the meat dry. Resting also allows the internal temperature to rise by another 5 degrees, ensuring the very center is perfectly warm.
Frequently Asked Questions
Can I cook a precooked ham from frozen?
It is not recommended to heat a frozen precooked ham directly in the oven. The outside will likely burn or dry out before the center even begins to thaw. For the best results and the most accurate timing, you should thaw the ham in the refrigerator for 24 to 48 hours before you plan to heat it. If you are in a massive rush, you can use a cold-water bath to speed up the thawing process, but never use hot water.
How long do I cook a spiral ham without drying it out?
The key to a spiral ham is a lower temperature and plenty of moisture. Heat it at 275 degrees Fahrenheit or 300 degrees Fahrenheit rather than 325 degrees Fahrenheit. Plan for about 10 to 12 minutes per pound. By keeping the temperature lower and ensuring the ham is tightly wrapped in foil with liquid in the pan, you protect those thin slices from the dry heat of the oven.
Do I need to add water to the bottom of the pan?
While it is not strictly mandatory, adding about a half-cup of water, cider, or stock to the bottom of the roasting pan is highly recommended. This creates a steam-filled environment inside the foil wrap. Without this added moisture, the salty environment of the ham can cause the meat to lose its natural juices more rapidly, leading to a tougher texture.
Should I cover the ham with foil the entire time?
You should keep the ham covered for about 90 percent of the cooking time. The only time the ham should be uncovered is during the final 15 to 20 minutes if you are applying a glaze or if you want to crisp up the skin. Keeping it covered is the primary way to ensure the heat penetrates to the bone without scorching the exterior.
How long is leftover cooked ham good for?
Once you have reheated your ham and served it, any leftovers should be refrigerated within two hours. Properly stored in an airtight container or tightly wrapped in foil, cooked ham will stay fresh in the refrigerator for 3 to 5 days. If you cannot finish it by then, ham freezes exceptionally well for up to two months, making it a great addition to future soups, omelets, or casseroles.