How long do you hard boil one egg and each additional egg?
When hard-boiling eggs, the same amount of time is needed no matter the number of eggs. Large eggs need to stand in the hot water after the heat is turned off for 12 minutes, while medium-sized eggs need to be in the hot water for just 9 minutes. Extra large eggs should sit in the hot water for 15 minutes. Source: incredibleegg.org