Much of the layout and content taken directly from Formulas:Mana Regen
The rate at which health points regenerate is referred to as health regeneration. Akin to mana regeneration, there are many sources and characteristics of health regeneration.
The Health regeneration has Changed with Patch 4.0. "Health regeneration uses a new formula. Outside of combat, all classes seem to regenerate 0.75% of their maximum health per second before the effects of abilities." The text below may be out of date.
Spirit-based Regeneration
Every two seconds, there is one tick of health regeneration, the value of depending on class and spirit:
| Class | Health gained per tick |
|---|---|
 Druid |
Spirit * 0.09 + 6.5 |
 Hunter |
Spirit * 0.25 + 6 |
 Mage |
Spirit * 0.10 + ? |
 Paladin |
Spirit * 0.25 + ? |
 Priest |
Spirit * 0.10 + ? |
 Rogue |
Spirit * 0.50 + 2 Confirmed at level 60 patch 1.09 |
 Shaman |
Spirit * 0.11 + 7 |
 Warlock |
Spirit * 0.07 + 6 |
 Warrior Pre-BC |
Spirit * 0.80 + 6 |
| Warrior BC |
Spirit * 0.50 + 6 |
- Health Regeneration is increased by 33% while sitting.
- Trolls regenerate 110% of this amount while out of combat, and 10% of this amount while in combat.
- This information is out of date as of patch 2.4.0 (possibly earlier)
Combat
No health regeneration from spirit occurs during combat, with the exception of the troll (10% mentioned above). Restoration Shamans can also get this 10% when specced into Purification. So far it is unknown if this is a bug or not and if other healers get the same effect.
Despite this, items either say "Restores X health [every|per] 5 sec." or "+X Health Regeneration" (some TBC items) will regenerate health at all times (even during combat). One point of "Health Regeneration" is the same as 1 health every 5 seconds.