A 4-pound meatloaf needs to bake at 350 F for two hours and 40 minutes. Check the meatloaf's temperature while it is still in the oven by inserting the thermometer into the center of the loaf. Meatloaf needs to be cooked to an internal temperature of at least 160 F.
The internal color of the meat is not a reliable indicator of doneness. Most meatloaf recipes include nitrate-rich vegetables, such as celery, carrots, onions or peppers, which prevent the ground beef from browning completely. Cover the meatloaf with aluminum foil and allow it to rest for an additional 10 to 15 minutes. During the resting period, the internal temperature will rise to approximately 165 F to 170 F.