Larger potatoes, such as russets, whites and yellows, should be microwaved on a high heat setting for approximately 10 to 15 minutes, depending on the size of the potato. Smaller potatoes, such as fingerling, red and purple varieties, require two to seven minutes on high.
When preparing a microwaved baked potato, cutting a small sliver in the potato or piercing it with a fork allows it to cook properly. When microwaving cut potatoes to make mashed potatoes or roasted potatoes, cut them into cubes, and put them in a microwave-safe dish covered with a lid or plastic wrap that has been pierced several times to allow proper ventilation. Microwave them on high heat for approximately 10 minutes. Some microwaves have a built-in baked potato setting that sets the cooking time based on the number of potatoes being cooked.