Reference

How hitcap.io works

Every calculator on this site is open math: the formula and breakpoint tables are generated straight from the same code the tools run — so the numbers here can't drift from the calculators.

Formulas

Combat rating converter

effect = rating / ratingPerUnit

Each combat rating converts to its effect by a fixed level-70 divisor — 15.77699 for melee hit, 12.62 for spell hit, 3.94 per expertise skill, 2.3654 per defense skill, 39.4231 per 1% resilience, and so on. These are Blizzard's canonical level-70 conversions.

Arena points

points = basePoints(rating) × bracketMultiplier

A logistic curve turns your rating into weekly base points; each bracket (2v2 0.76, 3v3 0.88, 5v5 1.00) scales it. The reverse tool inverts the curve by bisection, so it works for any monotonic profile. You only earn from your single best bracket — points do not stack.

Melee & spell hit caps

cap% = baseMiss(Δlevel) [+19 for dual-wield white hits]

Your miss chance depends on the target's level gap. +Hit subtracts from it; the cap is the hit% that drives miss to zero. Specials cap lower than dual-wield white swings (which carry a flat +19% penalty). Spell hit is a separate, steeper table that caps at 16% vs a +3 boss.

Expertise cap

expertise = floor(rating / 3.94);  dodge/parry removed = expertise × 0.25%

Each expertise skill point removes 0.25% dodge and parry from your target. Against a +3 boss the dodge cap is 26 expertise and the parry cap (front only) is 56.

Defense cap

skill = 350 + floor(rating / 2.3654);  critTaken% = max(0, baseCrit(Δlevel) − 0.04 × bonusSkill)

Defense skill above the 350 base removes 0.04% crit-taken per point. Crit immunity vs a +3 boss is the famous 490 defense skill; vs an even-level player it's 475.

Resilience

critChanceReduction% = rating / 39.4231;  critDamageReduction% = min(30, 2 × that)

Resilience reduces your chance to be critically hit (uncapped) and the bonus damage a crit deals (at twice the rate, capped at 30 percentage points in original TBC).

Armor penetration cap

armorIgnored = rating × 5.92;  remainingDR% = armor / (armor + 10557.5)

TBC armor penetration ignores a flat amount of the target's armor (not a percentage — that's WotLK). The cap is the target's effective post-debuff armor. The damage-reduction curve uses Blizzard's level-70 armor constant.

Haste rating & GCD cap

haste% = rating / 15.77;  GCD = max(1.0, 1.5 / (1 + haste%/100))

Haste rating converts at 15.77 per 1% (melee and spell). The global cooldown shrinks from 1.5s but never below 1.0s — reaching that floor (the GCD cap) takes 50% haste, about 789 rating.

Breakpoint tables

These tables are generated at build time by running the live calculator functions — they always match the tools.

What 100 rating buys (level 70)

Stat	100 rating	Per 1 unit
Melee hit	6.34%	15.77699 rating
Spell hit	7.92%	12.62 rating
Melee / ranged crit	4.53%	22.0769 rating
Spell crit	4.53%	22.0769 rating
Melee haste	6.34%	15.77 rating
Spell haste	6.34%	15.77 rating
Expertise	25 expertise	3.94 rating
Dodge	5.28%	18.9231 rating
Parry	4.23%	23.65 rating
Block	12.68%	7.8846 rating
Defense	42 skill	2.3654 rating
Resilience	2.54%	39.4231 rating

Arena points by rating — TBC Anniversary (Season 1)

Rating	2v2	3v3	5v5
1500	845	978	1111
1800	1632	1890	2147
2000	1834	2124	2413
2200	1875	2171	2467
2400	1882	2179	2476

Melee hit rating → %

Hit rating	Melee hit %
50	3.17%
100	6.34%
142	9.00%
200	12.68%
300	19.02%

Spell hit cap by target level

Target Δlevel	Cap %	Rating
Even (PvP)	4%	51
+1	5%	64
+2	6%	76
+3	16%	202

Expertise caps (vs +3 boss)

Cap	Expertise	Rating
Dodge (soft)	26	103
Parry (hard, front)	56	221

Defense crit-immunity threshold

Target	Defense skill	Rating
Even (PvP)	475	296
+1	480	308
+2	485	320
+3	490	332