A roast beef can be cooked in a Crock-Pot for eight to 10 hours on a low setting. If the Crock-Pot is on a higher setting, it can cook in only four to six hours. The general cook time is about 30 minutes per pound of meat.
The low setting on the Crock-Pot generally reaches 200 to 250 degrees Fahrenheit, while the high setting can reach 300 to 350 degrees Fahrenheit. It is important to make sure the meat is cooked all the way through before serving and eating it. If it is not cooked long enough at the right temperature, it may contain bacteria and germs that could lead to a food-borne illness.