Start Cooking recommends cooking a pork roast in the oven at 450 degrees Fahrenheit for 10 minutes and then reducing the temperature to 250 degrees Fahrenheit. The roast then cooks for another 50 to 80 minutes, depending on its size.
Cooks can use a meat thermometer to determine when the pork roast is done. The roast should reach an inner temperature of 145 degrees Fahrenheit followed by a three-minute rest. The pork continues heating during the rest time, making it safe to eat even though it still may have a pink color. Frequent hand and surface washing, as well as prompt refrigeration of unused pork, are also important for food safety.