time it takes to cook an average sized hen's egg in water. Hard-boiled eggs take longer to cook. The three minute egg timer is for soft-boiled eggs. The egg changes rapidly during the first few minutes of cooking. The changes cannot be seen through the eggshell, so timing is important. Other timers Countdown timers not specifically for eggs are also available for general kitchen and timing use. For example, the clockwork Memo Park Timer had a countdown of up to sixty minutes and was sold attached to a keyring, its original purpose being to remind motorists when their parking meter was due to expire. References Timers Kitchenware