How Long to Cook a 18lb Turkey: Timing Chart and Step-by-Step Plan

By Bennett Marlowe

An 18-pound turkey usually needs about 4 to 4 and a half hours in a 325°F oven when it is unstuffed and fully thawed. This guide gives you a realistic time range, the internal temperatures that confirm it is safe to eat, and a day-of schedule so every dish lands on the table at the same time. Whether you are roasting for the first time or adjusting a family recipe, you will know exactly how long to cook a 18lb turkey and how to tell when it is done.

Quick answer: cooking times for an 18lb turkey

Times vary with oven accuracy, pan type, starting temperature and whether the bird is stuffed. Use the ranges below as a planning guide, then trust your thermometer over the clock.

The USDA recommends cooking all turkey to an internal temperature of 165°F. Most cooks pull the bird a few degrees earlier and let it rest, because carryover heat will continue to raise the temperature.

Before you start: prep that affects cooking time

Good timing starts two or three days before the meal. A few decisions made early will change how long the bird takes in the oven.

Thaw the turkey completely

A frozen or partly frozen bird cooks unevenly and can spend too long in the unsafe temperature zone. Plan on roughly 24 hours of refrigerator thawing for every 4 to 5 pounds, which means an 18-pounder needs about 4 to 5 days in the refrigerator. If you are short on time, cold-water thawing takes about 30 minutes per pound with the water changed every half hour. Check the full process in How to Thaw a Turkey Safely: Refrigerator, Cold Water and Microwave.

Decide on stuffing

Cooking stuffing inside the bird adds at least 30 minutes, and the stuffing must reach 165°F on its own. Many cooks bake stuffing in a separate dish for easier timing and more reliable food safety. If you do stuff the bird, keep the cavity loose and use a thermometer in the center of the stuffing before serving.

Bring the bird closer to room temperature

Set the turkey on the counter for 30 to 45 minutes before it goes into the oven. This does not mean leaving it out for hours. A slightly cooler start simply helps the thighs catch up with the breast.

Step-by-step: cooking an 18lb turkey

Step 1: Preheat and position the rack

Heat the oven to 325°F. Place the rack in the lower third of the oven so the bird sits in the center. Make sure the rack will not touch the sides of the oven. Allow at least 30 minutes of preheating, because a cold oven adds unpredictable time.

Step 2: Prepare the bird

1. Remove the neck and giblets from the cavities and save them for stock. See How to Make Turkey Stock From the Carcass for a simple method.
2. Pat the skin dry with paper towels. Dry skin browns better.
3. Rub softened butter or oil over the skin and season generously with salt and pepper.
4. Tuck the wing tips under the breast and tie the legs loosely with kitchen twine.

Step 3: Set up the pan

Use a sturdy roasting pan with a V-rack so air circulates under the bird. Add about a cup of water or stock to the bottom of the pan to keep drippings from scorching. A roasting pan with handles that are easy to grip will make the transfer much safer. Compare options in How to Choose a Roasting Pan for Turkey: Size, Material and Rack.

Step 4: Roast in stages

Put the turkey in the oven breast side up. Plan on these checkpoints:

• At 1 hour: Rotate the pan 180 degrees for even browning.
• At 2 hours: If the skin is browning too fast, loosely tent the breast with foil.
• At 3 hours: Begin checking the internal temperature. Start with the thickest part of the thigh.
• Final stretch: Baste with pan juices every 30 minutes if you like, though basting is not required for juiciness.

Step 5: Check the temperature correctly

Insert an instant-read or leave-in probe thermometer into the thickest part of the thigh, without touching bone. Check the deepest part of the breast as well. Both should read 165°F, and the breast will often reach that point sooner. Full placement tips appear in How to Use a Meat Thermometer for Turkey (and Where to Insert It).

Step 6: Rest before carving

Move the turkey to a cutting board and tent it loosely with foil. Rest it for at least 30 minutes, and up to 45 minutes for a bird this size. Resting lets the juices settle back into the meat. This is also the perfect window to finish gravy and reheat sides.

Sample holiday timeline for an 18lb turkey

If you plan to serve at 5:00 p.m., work backward from the carving time. This schedule assumes an unstuffed bird roasted at 325°F for about 4 hours and 15 minutes.

For help with the carving step, see How to Carve a Turkey: Knives, Boards and Step-by-Step.

Factors that change cooking time

• Oven accuracy: Many home ovens run 15 to 25 degrees off the dial. An inexpensive oven thermometer can prevent a bird from finishing an hour late.
• Starting temperature: A bird straight from the refrigerator needs more time than one that has rested on the counter briefly.
• Pan material and color: Dark metal pans absorb heat faster. Stainless steel and light-colored pans may slow browning.
• Opening the door: Each time the door opens, the oven loses heat. Limit basting and peeking.
• Altitude: At higher elevations, water boils at a lower temperature, so the bird may take a little longer.
• Brining: A brined bird may cook slightly faster because its moisture content is higher. Read How to Brine a Turkey Safely before you start.

Common mistakes to avoid

• Relying on the pop-up timer alone. Many pop-up timers are set higher than 165°F and can be unreliable.
• Cooking a partially frozen bird and expecting even results.
• Stuffing the bird loosely and assuming the stuffing is safe because the turkey is done.
• Skipping the rest period, which causes juices to run out when carving.
• Covering the bird tightly with foil for the entire roast, which steams the skin instead of browning it.
• Leaving the turkey out on the counter for more than two hours during prep and serving.

Tips for juicy, evenly cooked turkey

• Start checking the temperature early. A thigh that reads 150°F at the three-hour mark will need closer monitoring.
• Use a probe thermometer with a cable and alarm so you can keep the oven door closed.
• If the breast reaches 165°F before the thighs, tent it with foil and continue roasting the legs.
• Save the drippings for gravy. Skim off the fat and whisk the remaining juices with stock and flour or cornstarch.
• Store leftovers within two hours of serving, in shallow containers, and use them within three to four days.

Recommended gear

A few tools make the difference between a predictable roast and a stressful one. These items support the timing plan described above.

• Leave-in probe thermometer: A wired probe with an alarm lets you monitor the thigh and breast without opening the oven. View on Amazon
• Heavy roasting pan with V-rack: The rack lifts the bird so heat reaches the underside, and sturdy handles make lifting an 18-pound bird easier. View on Amazon
• Oven thermometer: A standalone oven thermometer confirms whether your dial matches the actual temperature. View on Amazon
• Instant-read thermometer: Useful for quick checks in the thigh and breast late in the roast. View on Amazon

FAQ

How long does an 18lb turkey take to cook at 350°F?

At 350°F, an unstuffed, thawed 18-pound turkey typically takes about 3.5 to 4 hours. Start checking the temperature at about three hours, because higher heat can brown the skin before the thighs are done.

Should I cook an 18lb turkey covered or uncovered?

Most cooks roast uncovered for browning and then tent the breast with foil if it darkens too quickly. Keeping the bird covered the whole time will steam the skin and delay browning.

Is it safe to cook a turkey from frozen?

The USDA advises thawing turkey before cooking. Cooking from frozen takes much longer and makes it harder to heat the bird evenly to a safe temperature throughout. Thaw in the refrigerator or in cold water.

How do I know the turkey is done without a thermometer?

Juices should run clear when the thigh is pierced, and the leg should move easily at the joint. These signs are not reliable on their own. A thermometer reading of 165°F is the safest way to confirm doneness.

Why is my 18lb turkey taking longer than expected?

Common reasons include a cold starting temperature, an oven running cool, frequent door opening, or a bird that was not fully thawed. Check your oven with a standalone thermometer and use a probe to track progress.

How long can a cooked turkey sit out before serving?

Cooked turkey should not sit at room temperature for more than two hours. If the room is very warm, the limit drops to one hour. Keep hot food above 140°F with a warming tray or move it back into a low oven.

Can I cook an 18lb turkey in a convection oven?

Yes. Reduce the oven temperature by about 25°F from the conventional setting and begin checking the bird earlier, since convection cooks faster. Use the thermometer as your final guide.

Should a 18lb turkey be cooked breast side up or down?

Breast side up is the standard approach and works well for most home ovens. Some cooks flip the bird partway through to help the breast stay moist, but this adds handling and risk, so it is optional.

Conclusion

An 18-pound turkey generally needs about 4 to 4.5 hours at 325°F when unstuffed and fully thawed. Confirm doneness with a thermometer at 165°F in the thigh and breast, and rest the bird for at least 30 minutes before carving. Build your timeline backward from the meal time, and your bird will be ready when everyone else is. For a consult on food safety questions specific to your household, your local extension office or a registered food safety professional can help.

Related reading

• How Long to Cook a 20 Lbs Turkey: Timing Chart and Step-by-Step Guide
• How Long to Cook a 19lb Turkey: Timing, Temperatures and a Full Schedule
• How Long to Cook a 12lb Turkey: Times, Temps and a Timeline
• How Long to Cook Turkey With Stuffing: Times by Weight and Safe Temps

About Bennett Marlowe

Bennett focuses on practical advice for holiday cooking & baking: what matters before you buy, what to skip, and how to get more out of what you already own.