From Diablo Wiki
EHP = Effective Hit Points. (Or Effective Health Pool.)
This number rates a character's total survival power, combining hit points, resistance, life regeneration, life steal, blocking, dodge, defense, and more. A character's EHP value provides much more useful information than the hit points displayed in-game, since it evaluates a character's survive potential in actual combat.
The highest EHP values belong to Barbarians since they can attain such enormous Defense, plus higher life steal than any other class.
Hardcore characters generally carry much higher EHP than softcore (for obvious reasons) and values over one million for high level characters are not uncommon. Maximum EHP values (as of Patch 1.0.8) stretch up to about four million, though the highest values are on novelty characters built purely to buff this stat at the expense of DPS or general functionality.
- A listing of the highest EHP characters.
EHP is a complicated stat arrived at by factoring multiple values into one number. It can not be seen in the game or easily estimated in your head. To view your character's EHP in Diablo 3 you must use third party sites and tools.
- Character ladders and trackers like Diablo3Ladders.com display every character and item and automatically calculate all useful stat values, including EHP.