Things You'll Need
Ask 10 people how to hard-boil an egg and you're likely to get 10 varying answers. Everyone who's done much cooking has his own method, but not everyone considers the size of the egg. Perfectly cooked hard-boiled eggs require a certain amount of time in the scalding water; the bigger the egg, the more time it takes to become perfectly hard-boiled. When you know the amount of time required to hard-boil an egg depending on its size, you'll have a foolproof method of hard-boiling your eggs perfectly every time.
Place eggs in the bottom of a cooking pot and add enough cold water so that the water surface is at least 1 inch above the eggs. You can cook one egg or as many as will fit in a single layer in the pot.
Cover the pot with a tight lid. Put the pot on a burner. Turn the burner on high and allow the water to come to a rapid boil.
Remove the pot from the burner to prevent further boiling. Do not remove the lid. Start timing the eggs at this point, using a quality kitchen timer or the timer on your cooking stove. Let the eggs steep in hot water in the cooking pot according to their size: Steep medium eggs for 12 minutes, large eggs for 15 minutes, extra-large eggs for 18 minutes or jumbo eggs for 21 minutes. Timing is the most important component of cooking a hard-boiled egg.
Cool the eggs in cold water immediately after the time expires. Cooling eggs immediately prevents darkening around the yolks and makes eggs much easier to peel.
Crackle each egg all over by tapping it gently on the edge of the sink or on the countertop. Roll the egg gently between your hands to loosen the shell. Then peel the eggs under cold running water, starting at the largest end of each egg.
Do not use fresh eggs to make hard boiled eggs if possible; they are impossible to peel. Instead, use eggs purchased at least a week before you plan to prepare them.