Don't forget to peirce the skin, or it will explode. Prick it a couple of times with a fork.Certainly depends on how many potatoes and your microwave. Start it at 3-5 minutes - turn the potato and hit it for another 3-5 minutes. Let the potato rest and it will cook with residual heat. If you aren't looking for crispy skin, wrap it plastic wrap, it will keep the inside moist. Be sure to puncture the potato - makes a mess if you don't.