How long do you cood a 3lb roast at 275?

To cook a 3-pound roast at 275°F, you should plan for approximately 3 to 4 hours, depending on the type of meat and your desired level of doneness. Using a meat thermometer is the best way to ensure it reaches the appropriate internal temperature (e.g., 145°F for medium-rare beef). It's also a good idea to let the roast rest for about 15-20 minutes after cooking before slicing.