Attack rating

[Chesspiece_face]

this is off the top of my head but i believe an AR of 12000+ will do well into the upper lvls of hell. beggining of act 5ish. That's about 90%. Remember, though, that more importantly than your AR is your lvl compared to the stuff you are fighting. If you take it at a reasonable pace you shouldn't have much of a problem obtaining decent hit%.

there are lots of other factors as well.