The standard time to boil an egg in an egg cooker is approximately 6 to 7 minutes for a hard-boiled egg and 4 to 5 minutes for a soft-boiled egg. This duration ensures that the egg is fully cooked without overcooking, which can lead to a rubbery texture. The precise timing can vary slightly depending on the egg cooker's capacity and the desired level of doneness.

The reason for these specific times lies in the cooking process and the properties of eggs. When an egg is boiled, heat is transferred to the egg white and yolk, causing them to expand and coagulate. The cooking time is crucial because it determines the internal temperature of the egg, which affects its texture and taste. According to the United States Department of Agriculture (USDA), the minimum internal temperature for a hard-boiled egg is 160°F (71°C), which is typically reached within 6 to 7 minutes. For a soft-boiled egg, the internal temperature should be around 140°F (60°C), which can be achieved in 4 to 5 minutes. Overcooking an egg beyond these temperatures can result in a tough and less enjoyable texture. Additionally, the size of the eggs and the initial temperature of the water can also influence the cooking time. Larger eggs or cooler water may require slightly longer cooking times.