How does mana regeneration work?

Your mana regenerates all of the time, except for a period of five seconds after you start casting a spell (thanks to Sherman for the correction here). In this five seconds, you have no regeneration. This is commonly called the five second rule. A spell here is defined as anything that costs mana to cast.

One interesting note is when spells *don't* cost mana, they will not start this timer, and you will continue to regen mana. Nature's Swiftness costs no mana, and will not invoke the five second rule. Spells casted with the clearcasting state from the Elemental Focus talent also will not start the five second timer.

Totems, on the other hand, will start the five second timer.

Mana regenerates according to how much spirit you have. Take the amount of spirit you have, and divide it by five. Then add 17 to this value. That is around how much mana you should regenerate ever tick ( 2 seconds). You do not mana regen faster if you are sitting down or standing up. You do not mana regen faster in battle or out of battle.

(However, Spirit for Shaman isn't really that good. Mana/5 is much better, and a good amount of our gear uses it. When looking for Enchants, go Mana/5 over Spirit.)