Edit: this post was written in 2008. The principles are the same, but the actual numbers were updated in the pre-Cataclysm patch 4.01. After reading this post to learn the mechanics, go here to see the updated numbers.
s have been buffed, but in the early stages of gearing up
its still a vital stat to look for in your gear.
Warning, some math to follow. Pass this point with caution.
As dual wielders, we take a significant penalty to hit. Without any hit rating, we would miss so often that our dps would suffer greatly. More hits = more damage, of course, but it also means more combo points, more poison procs, more talent procs, etc… In PvE instancing and early raiding, there is no single stat that has as large an effect on your damage as hit rating.
While leveling, its nice to get some hit rating, but you don’t need to focus on it. Once you get to 80 and you are doing heroics and raids, then you will want to find gear with hit rating. How much do you need?
There is no magic number. Some classes try to be hit-capped, meaning that they will never miss. For rogues (and fury warriors, ret paladins, and dual-wielding shamans) that’s out of reach for now. Get as much as you can without making huge sacrifices to Agility, Attack Power, Crit Rating, Haste, etc..
There are three separate miss chances – one calculation for white damage, another for special attacks, and a third for poisons (treated as a spell).
For special attacks, the chance to miss is 9% 8% against raid bosses. (edit: changed in Wrath)
For regular attacks (white damage) at level 80, the chance to miss when dual wielding is
24% 23% + (Defense Skill - Weapon Skill)*.1%
Unless the opponent’s defense skill is more than 10 points higher than your weapons skill. If that is the case then the equation is
26% 25% + (Defense Skill - Weapon Skill - 10)*.4%
Translated to simple percentages, that will mean a 24% 23% chance to miss against a level 80 foe, a 25% 24% chance to miss against a level 82 boss (heroics) and a 28% 27% chance to miss a level 83 raid boss with your autoattacks (white damage). So, to be completely hit-capped you would have to have enough hit rating to reduce your chance to miss by 28% 27%. (edited to reflect reduced dual wield penalty in Wrath)
Poisons are treated as a spell. Pre-Wrath we didn’t worry about this. Now that spell hit and melee hit have been combined we can use our hit rating to reduce the rate that our poisons are resisted (miss). At level 80, the chance to miss with a spell is 17%.
Pause, take a deep breath. More math coming.
The amount of +hit% that you get from hit rating changes with level. That’s one way that Blizzard scales the combat system. The numbers that you got used to pre-Wrath are no longer valid. (I remember going into Karazhan with 270 hit rating and thinking that was awesome. Now, not so much.)
The conversion from hit rating to hit % is now this: For a level 80 character, 32.77 hit rating = 1% reduction in chance to miss for melee combat.
Assuming that you have maxed your weapon skill at 400 when you get to level 80, then…
- The first +hit milestone is to reduce your chance to miss by 9% 8%. That will mean that your special attacks never miss on raid bosses. To do that you need 295 262 hit rating. However, many (if not all) rogues will take 5/5 in Precision. If so, it reduces that required hit rating to 131 99. Easy enough. You’ll get that much hit rating without even trying if you have decent gear. (edited due to new hit table in Wrath)
- Next is the Poison cap. This means that your poisons will never miss (be resisted). You need 17% for that. However, this uses the hit rating conversion for spells rather than melee. That conversion is 26.23 hit rating = 1% at level 80. So we would need 446 hit rating without Precision, or 315 with Precision.
- The next one is to never miss with auto-attacks (white damage). You would need 28% 27% for that, which is a whopping 918 885 hit rating if you have not taken any points in Precision. With the Precision talent factored in, it drops to a still-high value of 754 721. You could eat some Snapper Extreme to get 40 points toward that total, but you still aren’t going to be hit-capped any time soon. (edited due to new hit table in Wrath)
In light of this, you are probably expecting that level 80 gear is going to loaded with huge quantities of +hit rating to get you to 721, right? Umm… not so much. Some items have high +hit. However, its not so high that you should be shooting for the hit cap. After you have the initial 8% so your specials won’t miss, make sure you balance out your stats.
The best advice is make sure you are above the “special attacks” cap, and try to be above the “poison cap” if possible (especially for Mutilate rogues). After that, you’re probably going to want to work on agility and crit rating rather than hit rating, because you don’t get as much benefit from stacking hit rating.
(I know, I know, TL;DR)