TBC Defense Cap Calculator
Find the defense rating you need for crit immunity — the classic 490 defense tanking benchmark — against even-level, PvP and +3 boss targets.
Your crit-immunity cap
You have 392 defense skill — still 3.92% crit chance taken. Add ≈ 232 more defense rating to reach the 490-skill immunity threshold.
Advanced: formula & source
skill = 350 + floor(rating / 2.3654); critTaken% = max(0, baseCrit(Δlevel) − 0.04 × (skill − 350))
Each defense skill point above the level-70 base of 350 removes 0.04% chance to be critically hit, and separately adds 0.04% dodge, parry, block and chance-to-be-missed (uncapped by crit immunity, and not adjusted here for diminishing returns). Against a +3 raid boss the well-known crit-immunity threshold is 490 defense skill. 2.3654 defense rating = 1 skill point.
How TBC defense works
Defense skill reduces your chance to be critically hit. At level 70 your base skill is 350, and every point above that removes 0.04% crit chance taken — until it hits zero. Against a +3 "boss" (level 73) that means 490 defense skill; against an even-level (PvP) target it's 475. At level 70, 2.3654 defense rating = 1 skill point.
The same skill also adds dodge, parry, block and chance-to-be-missed at 0.04% per point — that part keeps scaling past the crit-immunity threshold, which is why tanks often stack well beyond 490.
Frequently asked questions
What is the defense cap in TBC?
It's the defense skill that makes you immune to critical hits from a given target — the famous number is 490 defense skill against a +3 "boss" (level 73) target, where 350 is your base skill at level 70 and the remaining 140 points (≈332 defense rating) cancel the boss's 5.6% bonus crit chance against you.
Does defense do anything besides stop crits?
Yes. Every point above the 350 base also adds 0.04% dodge, parry, block and chance-to-be-missed — uncapped by crit immunity, so stacking past 490 keeps adding avoidance (subject to the game's usual diminishing returns on those stats, which this calculator does not model).
Is the defense cap the same for PvP?
The mechanic is the same, but the target is weaker: an even-level player only has a 5% base crit chance against you (vs 5.6% for a +3 boss), so the PvP crit-immunity threshold is 475 defense skill, not 490.
How does defense rating convert to defense skill?
2.3654 defense rating = 1 skill point at level 70, on top of the 350 skill every level-70 character starts with.