Egg cycle

An Egg cycle (Japanese: タマゴのサイクル Egg cycle) is a unit of time measured in steps that determines how long it will take for a Pokémon Egg to hatch. The number of Egg cycles required to hatch an Egg is stored in the same number that would be the friendship value for normal Pokémon. In all games since Generation V, the length of an Egg cycle is 257 steps. In Generation IV, Egg cycles were 255 steps long, while in Generations and, they were 256 steps long.

Generation V and later
Every time an Egg cycle is completed, the Egg cycle count for all Eggs in the player's party is decreased by 1 (by 2 if a Pokémon with or  is also in the party, but not below 0). An Egg is ready to hatch as soon as its Egg cycle count reaches 0. If multiple Eggs are ready to hatch after an Egg cycle ends, the first Egg in the party will hatch immediately, while the remaining Eggs will hatch&mdash;in order and one at a time&mdash;each time the player takes another step.

Using a Hatching Power (from or O-Powers) will shorten the length of an Egg cycle depending on the strength of the Power used. The number of steps walked in the current Egg cycle is also modified by the appropriate multiplier above. When the Hatching Power wears off, the current number of steps walked in the current Egg cycle is divided by the same multiplier.
 * Weak: 4/5 (205 steps)
 * Medium: 2/3 (171 steps)
 * Strong: 1/2 (129 steps)

In, Secret Pals at the player's Secret Base can decrease an Egg's current Egg cycle count by half of its base Egg cycle count, rounded up. In, the hot springs at Poké Pelago's Isle Avue can decrease an Egg's Egg cycle count over time.

Generations III and IV
Every time an Egg cycle is completed, the game goes through the Eggs in the player's party in order and performs the following: As a consequence of this logic, in order to hatch a given Egg, the player must walk one more Egg cycle than the Egg's base Egg cycle value. As an example, a new Egg has an Egg cycle value of 5, but the player must walk 6 Egg cycles in order to hatch it. By the same token, if a Pokémon with or  is in the party, instead of an Egg taking   (rounded up) Egg cycles to hatch,   (rounded up) Egg cycles must be walked.
 * If the Egg's Egg cycle count is 0, the Egg hatches and no other Eggs are processed.
 * Otherwise, subtract 1 from the Egg's cycle count.
 * In or Generation IV games, if a Pokémon with  or  is in the party, subtract 2 instead of 1 (but to no less than 0).

When an Egg is received from the Day Care Man, the counter for the current number of steps taken in the current Egg cycle is set to 1 in Generation III or to 0 in Generation IV.

Generation II
Every time an Egg cycle is completed, the game goes through the Eggs in the player's party in order and performs the following:
 * Subtract 1 from the Egg's cycle count. If its Egg cycle count is now 0, the Egg hatches and no other Eggs are processed.

Quotes
The quote shown from the table below depends solely on the Egg cycle value in the Egg's Pokémon data structure. That is, since, in Generations III and IV, the number of Egg cycles remaining for the player to walk before an Egg hatches is one greater than the value in the Egg's data structure, the maximum number of Egg cycles the player must walk is not the maximum shown in the leftmost cell, but one greater than that value. As an example, in, a new Egg has a base 5 Egg cycles and will show the quote "Sounds can be heard coming from inside! It will hatch soon!" on its summary screen, but the player will have to walk 6 Egg cycles before the Egg will hatch.

At Poké Pelago's Isle Avue, if the player has an Egg in the hot springs and taps it, Mohn will have a unique set of quotes about the Egg, but they will still correspond to the same intervals.