Ok, so, how long to cook a roast beef is not quite a super-simple formula. There are a few variables that you need to consider. These variables are as follows. Your beef roast may be fattier than beef roasts you’ve had in the past.

If your roast is fatty, then you want to cook the roast for less time than you would cook it if it were a solid piece of meat. Also, the shape will effect cooking times. If the beef roast is perfectly round, then the meat will cook more consistently.

Still, those are small variables that can be easily adjusted for. The simple formula for how long to cook a beef roast is as follows. At a consistent oven temperature of 350º, you want to cook the beef roast for about 45 minutes per pound.

Average beef roasts are about five pounds, so that means you will cook an average sized beef roast for 3 and ¾ hours. That will yield a medium to medium-well roast. If you prefer your beef roast a bit bloodier, then take some time off the cooking time. Remember, if your beef roast is bigger than average, then you are going to want to add more cooking time.