The condition of a game character gaining mana points over time is referred to as mana regeneration. Players can gain mana from basically two sources — out-of-combat or in-combat regeneration. Spirit regenerates high amounts of mana, but only out of combat; whereas combat regeneration is usually lower, but continues during combat.
The mana regeneration formula is uniform across all classes: 
- SpiritRegen(SPI,INT,LEVEL) = (0.001 + (SPI x sqrt(INT) x BASE_REGEN[LEVEL])) x 5
BASE_REGEN is a variable dependent on base mana and is summarized in the following table:
- CombatRegen = 5% of Base Mana†
- † Base-line mana in combat is mana with INT at 0 (zero).
Direct forms of mana regeneration (previously called MP5) was removed from all items, spells and talents in Patch 4.0.1. There will be the occasional fixed point mana regen legacy item; but mana regen will mostly be affected by Intellect and Spirit bonuses.
Other sources of mana include instant (such as Mana Potions and certain abilities like ), sporadic (such as ), and temporary (such as ).
Spirit will be the primary modifier of mana regen while out-of-combat and only based on affect to base mana in-combat.
- Mana regeneration is not affected by sitting down or standing up
- Five-Second-Rule removed. Its is now "Mana Regen while out of combat" and "Mana Regen while in combat", instead of "Mana Regen while not casting" and "Mana Regen while casting".
- Spirit Regen formula is unchanged.
- In the beta build 220.127.116.1102, the BASE_REGEN coefficients for levels 81-85 remain the same as level 80 at 0.003345.
- / Patch 4.0.1 (12-Oct-2010): MP5 and 5-second rule were removed from the game, regen may still be calculated in 5 sec increments.
- Patch 3.1.0 (14-Apr-2009): Mana Regeneration: The amount of mana regeneration derived from Intellect and Spirit has been reduced by 40%; however, talents that allow for mana regeneration while in combat have been increased. As a result, in-combat regeneration for classes with those talents will stay the same, while out-of-combat regeneration will be lower.
- Patch 2.4.0 (25-Mar-2008): Spirit-Based Mana Regeneration: This system has been adjusted so that as your Intellect rises, you will regenerate more mana per point of Spirit.
- Patch 1.4.0 (2005-05-05): Mana regeneration is now disrupted when a spell has completed casting rather than at the start of casting. It will resume normally five seconds after the last spell cast. This change increases the total time spent regenerating mana and therefore increases the total contribution from Spirit for mana-based classes.
- See also: Spirit