How long to bake sweet potatoes Sweet potatoes will bake for about 45 minutes to an hour in a 400 degree F oven. I baked my 2 medium sized potatoes for 1 hour. Adjust the time if your potatoes are larger or smaller. If you're unsure when they're done, the inside should read 210 degrees. My digital kitchen thermometer is one of my favorite tools! My potatoes were perfectly tender and had a fantastic roasted flavor.