Energy Boost

Energy Boost is a permanent upgrade that increases the maximum energy at the end of each stage. The maximum energy calculation are based on each cookie's maximum energy and the Energy Boost level. For example, for Brave Cookie Lv. 8 which has 100 energy when combined with Energy Boost Lv. 30 will make the cookie has a maximum energy bar of 250 Energy.

Energy Boost will not increase the Energy Potion or Cookie Revival rate, because both energy bonuses are producing extra energy at a fixed rate. However, Energy Upgrade may affect on longer Relay Cookie energy, because Relay Cookie's initial energy are counted on the relay cookie's energy added with Energy Boost level, then divided by 2. For example, for Brave Cookie Lv. 8 and Energy Boost Lv. 30 will make the relay start with 125 Energy.

There are no other way to increase maximum energy without using treasures that makes extra maximum energy, for example Foxy Bead's Heart. Be careful that some treasures that gives extra energy either at main cookie or relay cookie will never exceed the maximum energy. For example, if you have maximum 250 Energy and you take a relay with 170 Energy, combined with a treasure/items with 200 Energy bonus will make your relay start with 340 Energy, not 370 Energy. It is because relay cookie's maximum energy is twice the initial relay energy (170 x 2 = 340) and energy bonus will not exceed the maximum energy.

Upgrade
The upgrade consists of 60 levels. Originally it has only 20 levels at first season, 30 levels at the second season, and 40 levels at the Edge of the World season. The latest update was added on New World season, twice. The first was added on 18 December 2014 with 50 levels and 27 March 2015, increasing it to 60 levels.

Each upgrade costs will be 500~600 coins in increment from the previous upgrade. It gives cookies an extra 5 energy as a bonus, then increases by 5 for each upgrade. When upgraded to Level 15, it allows the player to buy Knight Cookie with coin. When upgraded to Level 50, players are able to buy Apple Cookie.

This is a high priority for all new players that are starting to play.

Trivia

 * Whenever a Cookie is low on Energy, he or she will begin sweating. This is just visual and has no effect on gameplay. However, the sweat goes away if the Cookie has been revived and does not return regardless of remaining Energy level and the Relay Cookie does not sweat at all when low on Energy.
 * Several upgrading messages are allusions of famous quotes in TV, movies, and music.
 * The upgrading message for level 45 might be an allusion to the album series Now That's What I Call Music!.
 * Upgrading messages for levels 58 & 60 are both referring to the film series Star Wars.
 * The upgrading message for level 22 it might take reference to the song Harder, Better, Faster, Stronger by  Daft Punk.