Combat rating system

Combat rating is a mechanic introduced in patch 2.0.1 which are for combat stats on items that were previously percentage based. Rating is converted linearly to percentage; the number of rating points needed to gain one percentage point increases with level and varies depending on the stat, but is the same for all classes. Ratings were introduced because percentage based itemization would have scaled excessively when The Burning Crusade was released and the level cap rose to 70.

Combat rating types

The following combat ratings are currently in use:

Block rating Critical strike rating Dodge rating Expertise rating Haste rating

Hit rating Mastery rating Parry rating PvP Resilience rating PvP Power rating

Unlike fixed percentages such as 2% critical strike chance, combat ratings diminish in potency as characters increase in level. 2% crit is the same at every level, while 28 critical strike rating grants 4% crit at level 34, 2% crit at level 60, and 1.27% crit at level 70. This allows Blizzard the ability to create and add new and better items to the world without eventually reaching a point where every character has a 100% chance to critically strike.

All classes convert ratings into attributes at the same ratio. Below are the conversions for combat ratings at each expansion's level cap:

Rating	Effect	Level 60	Level 70	Level 80	Level 85	Level 90
Dodge	1% dodge chance	13.8	21.7615	45.202	176.71899	885.0
Parry	1% parry chance	13.8	21.7615	45.202	176.71899	885.0
Block	1% block chance	6.9	10.8808	22.6251	88.3594	295.0
Physical hit	1% hit chance	9.37931	14.7905	40.7548	102.446	340.0
Spell hit	1% spell hit chance	8	12.6154	26.232	102.446	340.0
Expertise	-1% Dodge/Parry and 1% Spell Hit	2.34483	3.69761	7.68869	102.446	340.0
Critical strike	1% critical strike chance	14	22.0769	45.906	179.28	600.0
Haste	1% haste	10	15.7692	32.79	128.05701	425.0
Mastery	1% Mastery	14	22.0769	45.906	179.28	600.0
PvP Resilience	-1% Damage from Players	9.292	14.652	30.467	92.316	310.0
PvP Power	1% Damage/Healing to Players	7.964	12.559	26.115	79.128	265.0

Level 90 Ratings are a work in progress. Derived from SimulationCraft datamining and beta testing.

Notes:

Diminishing returns

Avoidance stats suffer from diminishing returns ("DR"), meaning the rate of return for each point contributed from gear is not constant. The in-game tooltips will show the undiminished value, but the amount actually received is lower. Base stats and talents are not affected by DR, but stats from gear are diminished.

The formula to calculate the diminished part of a stat is as follows:

1    1   k
—  = — + —
x'   c   x

where:

x' is the avoidance after DR.

x is the avoidance before DR.

c is a class-specific cap of the stat.

k is also a class-specific constant.

The table containing the class-specific caps for parry (C_p) and dodge (C_d) is as follows:

	k	Cp	1/Cp	Cd	1/Cd
Death knight	0.9560	65.631440	0.01523660	65.631440	0.01523660
Druid	0.9720	N/A	N/A	116.890707	0.008555
Paladin	0.9560	65.631440	0.01523660	65.631440	0.01523660
Warrior	0.9560	65.631440	0.01523660	65.631440	0.01523660
Hunter	0.9880	145.560408	0.006870	145.560408	0.006870
Mage	0.9830	N/A	N/A	150.375940	0.006650
Priest	0.9830	N/A	N/A	150.375940	0.006650
Rogue	0.9880	145.560408	0.006870	145.560408	0.006870
Shaman	0.9880	145.560408	0.006870	145.560408	0.006870
Warlock	0.9830	N/A	N/A	150.375940	0.006650

See also

• Item level
• Attack table

Patches and hotfixes

• Patch 4.0.1 (2010-10-12): Mastery rating has been added as a new stat which provides unique benefits for characters based on class and talent specialization. Mastery rating does not currently exist on items in the game, however, Reforging can be used to add Mastery rating as a secondary stat to existing items.
  

The following stats have been removed from gear: attack power, spell power (with the exception of caster weapons), MP5, armor penetration, block value, defense (and defense rating), weapon skills.

• Patch 3.2.0 (2009-08-04):
  • Agility: The amount of agility required per percentage of Dodge has been increased by 15%. This change required recalibrating the amount of dodge a player has with 0 agility by a slight amount as well, so all players will see their dodge percentage vary a small amount.
  • Block rating: The amount of bonus block value on all items has been doubled. This does not affect the base block value on shields or block value derived from strength.
  • Dodge Rating: The amount of dodge rating required per percentage of dodge has been increased by 15%. This is before diminishing returns. Combined with other changes, this makes dodge rating and Parry rating equally potent before diminishing returns apply.
  • Parry Rating: The amount of parry rating required per percentage of parry has been reduced by 8%. This is before diminishing returns. Combined with other changes, this makes dodge rating and parry rating equally potent before diminishing returns apply. Parry still diminishes more quickly than dodge.
  • Resilience: No longer reduces the amount of damage done by damage-over-time spells, but instead reduces the amount of all damage done by players by the same proportion. In addition, the amount of resilience needed to reduce critical strike chance, critical strike damage and overall damage has been increased by 15%.
    
• Patch 3.1.0 (2009-04-14):
  • Armor Penetration Rating: All classes now receive 25% more benefit from Armor Penetration Rating.
  • Haste Rating: shamans, paladins, druids, and death knights now receive 30% more melee haste from Haste Rating.
    
• Patch 3.0.2 (2008-10-14):
  • Hit Rating, Critical Strike Rating, and Haste Rating now modify both melee attacks and spells.
  • All items and effects which grant bonuses to spell damage and spell healing are being consolidated into a single stat, Spell Power. This stat will appear with the same values found on items which grant "increased spell damage and healing" such as on typical Mage and Warlock itemization.
    
• Patch 2.3.0 (2007-11-13):
  • All items have had their bonuses to Weapon Skill Rating converted to a new stat called Weapon Expertise Rating. Each point of Weapon Expertise reduces the chance for your attacks to be Dodged or parried by .25%.
  • Healing: Almost all items and enchantments that provide bonus healing now also provide a smaller number (approximately 1/3) of bonus spell damage. There are a few items and enchantments where this was not possible, such as random-stat items and Zul'Gurub enchantments, but this is now the case on virtually all other items.
  • Weapon Skill: All items and abilities that granted weapon skill have been changed. In most cases, they were converted to expertise or expertise rating. Ranged attacks do not benefit from expertise, so ranged weapon skill has generally been replaced by critical strike bonuses or hit bonuses. In a few cases, talents have been changed to other effects to avoid granting players excessive amounts of expertise.
    
• Patch 2.2.0 (2007-09-25):
  • Resilience rating: The reduction to the percent chance to get a critical strike now also reduces the damage dealt by damage over time effects by the same percentage.
    
• Patch 2.1.0 (2007-05-22):
  • Spell Haste: The amount of spell haste rating needed per percentage of haste has been increased substantially. However, spell haste will now affect channeled spells, increasing the rate of their effects and decreasing their total duration. The same amount of damage/healing per casting will occur, but will take less time.
  • The amount of parry rating needed to get 1% parry has been reduced by 25%.
  • Dodge Rating: Low level players now calculate dodge from dodge rating at the same rate as level 34 players.
    
• Patch 2.0.1 (2006-12-05):
  • New item property "Resilience" has been introduced. Resilience reduces your chance to be the victim of a critical strike, and reduces the amount of damage critical strikes do to you.
  • Weapon Skill now does the following:
    • Weapon skill will no longer reduce the percentage damage lost due to glancing.
    • The player will gain 0.1% to their critical strike rating per weapon skill against monsters above their level.
  • Items that give bonuses, such as critical strike percentage, have been modified to adhere to a combat rating system.
  • All current items will provide the exact same benefit from ratings at level 60 as they provided before the ratings system.