Armor calculation

Armor calculation in Guild Wars is rife with inconsistencies. This article explains how it works, where there are bugs or anomalies, and offers some simple rules-of-thumb.

Categories
Armor bonuses and penalties are divided into 3 main categories:


 * Core armor, consisting of:
 * Basic armor,
 * Insignia,
 * Mysticism,
 * Base Shield armor, and
 * Inscriptions (actual inscriptions, not inherent mods that can be reproduced with inscriptions).


 * Bonus armor, consisting of:
 * All other weapon mods,
 * Inherent mods, including Unique (Green) item mods,
 * Consumables, and
 * Almost all armor-altering skills, with the exception of those in the Special Armor category.
 * Cracked Armor is an armor penalty included in this category.


 * Special armor, consisting of:
 * Bonuses: "I Am Unstoppable!", Illusionary Weaponry and Mantra of Signets, and
 * Penalties: Barbed Arrows, Healing Signet and Shadowy Burden.

Important wiki articles
Before you read the rest of this guide, you may want to brush up on the following mechanics and bugs:


 * General mechanics
 * Armor rating
 * Effect stacking


 * Bugs
 * Cracked Armor
 * Elemental and Physical Resistance, Aggressive Refrain and Soldier's Fury
 * "I Am Unstoppable!", Illusionary Weaponry and Mantra of Signets
 * Barbed Arrows, Healing Signet and Shadowy Burden

Step-by-step calculations
Follow the steps below to calculate your effective armor rating:

Step 1: Core armor
Add everything from the Core category.

Step 2: Bonus armor
Calculate your net Bonus armor by adding all bonuses and subtracting all penalties from this category, including the penalty from Cracked Armor.


 * If the net Bonus armor is 25 or lower, add its value to your Core armor.
 * Your Bonus armor can only lower your armor to 60, or to your Core armor, if that is lower than 60.
 * If the net Bonus armor is 26 or higher, check whether the highest Bonus armor bonus you have is more than 25.
 * If your highest Bonus armor bonus is higher than 25, add that value to your Core armor.
 * If your highest Bonus armor bonus is 25 or lower, add 25 to your Core armor.

Step 3: Armor Penetration
If Armor Penetration affects the damage, apply the relevant percentage to the armor rating you have now. (However, there are some additional, undetermined anomalies in Armor penetration; your actual values might differ by several percent.)

Step 4: Special armor
Finally, add all the bonuses and subtract the penalties from the skills in the Special armor category. (However, the total cannot be below zero.) The result is your effective armor rating.

Examples
To raise familiarity with Armor Calculation, here are a few examples of different situations.

Example 1
A paragon with 9 Command, max armor with Centurion's Insignia, a Spear of Defense and a Command Forgotten Shield, under the effects of Soldier's Fury and "I Am Unstoppable!", is hit with Lightning Orb. What is the effective armor rating of the paragon? By looking at the list of armor effects by category and following the steps above, calculating this is pretty straightforward.

Step 1: Core armor
Add everything from the Core armor category:
 * Basic armor: max paragon armor is 80
 * Insignia: the Centurion's Insignia trigger under Soldier's Fury: 10
 * Base Shield armor: the requirement for the Forgotten Shield is met: 16

Total Core armor: 106

Step 2: Bonus armor
Add all bonuses and subtract all penalties from the Bonus armor category:
 * Bonuses:
 * Inherent mod from the Command Forgotten Shield (it triggers versus Lightning Orb's lightning damage): 10
 * Of Defense mod from the Spear: 5
 * Penalties:
 * Soldier's Fury: 20
 * Cracked Armor (Lightning Orb inflicts Cracked Armor before doing its damage): 20

Net Bonus armor: –25

Because the net Bonus armor is lower than 26, add it to the Core armor: 106 – 25 = 81

Step 3: Armor Penetration
Apply the proper percentage of Armor Penetration.

Lightning Orb has 25% Armor Penetration: 81 × 0.75 = 60.75, rounded to 61

Step 4: Special armor
Finally, add the bonuses and subtract the penalties from the Special armor category:
 * Bonuses:
 * "I Am Unstoppable!": 24

Effective armor rating: 85

Example 2
A mesmer with 9 Inspiration Magic, non-max armor with an armor rating of 30 with Sentry's Insignia, a 40/40 set, under the effects of Elemental Resistance and Illusionary Weaponry (with 4 other Illusion skills on the skill bar), is hit with an arrow.

Step 1: Core armor
Add everything from the Core armor category:
 * Basic armor: non-max armor, in this case 30
 * Insignia: the Sentry's Insignia trigger because of the stance: 10

Total Core armor: 40

Step 2: Bonus armor
Add all bonuses and subtract all penalties from the Bonus armor category:
 * Penalties:
 * Elemental Resistance at 9 Inspiration Magic has a penalty versus physical damage: 17

Net Bonus armor: –17

Because the net Bonus armor is lower than 26, add it to the Core armor: 40 – 17 = 23

However, Bonus armor can only lower your armor to 60, or to your Core armor, if that is below 60. In this case, the Core armor is 40, and Bonus armor can only lower your armor to 40

Step 3: Armor Penetration
Apply the proper percentage of Armor Penetration.

In this case, there is no Armor Penetration, so this step is skipped.

Step 4: Special armor
Finally, add the bonuses and subtract the penalties from the Special armor category:
 * Bonuses:
 * Illusionary Weaponry with 4 other Illusion skills: 25

Effective armor rating: 65

Example 3
An elementalist with 8 Earth Magic, max armor with Blessed Insignia, a Spear of Enchanting and a (13 armor, requirement 8) Strength Shield with the inscription "Riders on the Storm", under the effects of Armor of Earth and Armor of Salvation, is hit with Lightning Orb.

Step 1: Core armor
Add everything from the Core armor category:
 * Basic armor: max elementalist armor is 60
 * Insignia: the Blessed Insignia trigger under Armor of Earth: 10
 * Inscription: "Riders on the Storm" triggers versus lightning damage: 10
 * Base Shield armor: the requirement for the Strength Shield is not met: 8

Total Core armor: 88

Step 2: Bonus armor
Add all bonuses and subtract all penalties from the Bonus armor category:
 * Bonuses:
 * Armor of Earth at 8 Earth Magic: 43
 * Armor of Salvation: 5
 * Penalties:
 * Cracked Armor (like above, Lightning Orb inflicts Cracked Armor before doing its damage): 20

Net Bonus armor: 28

Because the net Bonus armor is over 25, check whether the highest Bonus armor bonus is higher than 25. Armor of Earth is, with 43.

Adding that value to the Core armor gives 131

Step 3: Armor Penetration
Apply the proper percentage of Armor Penetration.

Lightning Orb has 25% Armor Penetration: 131 × 0.75 = 98.25, rounded to 98

Step 4: Special armor
Finally, add the bonuses and subtract the penalties from the Special armor category. None are applicable in this case.

Effective armor rating: 98