Damage Conversion Explained: How to Read Conversion Lines on Builds

What conversion is

The mechanic that lets a Physical skill power a Fire build - a core tool of build crafting.

• ▸Damage Conversion reassigns the stated percentage of an attack's flat damage to another type. Example: '200 Physical' with '30% Physical to Fire' yields 60 Fire and 140 remaining Physical.
• ▸Conversion comes from three families of sources: conversions on the skill itself or via item skill modifiers (local), character-wide conversions on gear and devotions (global), and weapon armor piercing (Physical to Pierce).
• ▸Damage-over-time converts the same way - unless the destination type has no matching DoT (e.g., Burn under a Fire-to-Chaos conversion), in which case that DoT stays unconverted.
• ▸Conversion is capped at 100%; anything beyond never increases the damage above its original amount.
• ▸If multiple destinations from one type total over 100%, the damage splits by the ratio of the rates (e.g., '100% Physical to Fire' plus '200% Physical to Acid' becomes roughly 33.3% and 66.7%).

Processing order: local, then global, then armor piercing - no re-conversion

This order decides which conversion wins - and explains why some conversions seem to do nothing.

• ▸Each flat damage instance is processed through three steps: local (skill-side), global (gear-side), then armor piercing.
• ▸Once converted, damage is never converted again - each step only touches what the previous steps left unconverted.
• ▸That is why a skill-side '100% Vitality to Aether' local conversion makes any gear-side 'Vitality to X' global conversion do nothing for that skill: no Vitality remains.
• ▸The same conversion from multiple sources adds up within a step (e.g., 30% on the weapon plus 40% on the chest = 70% global), but rates never add across steps.
• ▸Armor piercing is the final step, converting weapon Physical damage to Pierce. On current versions every armor-piercing weapon has a 100% piercing rate, and it only applies to attacks that reference weapon damage.
• ▸Damage converted to the same type in different steps stays split as independent flat instances. Against armor's per-instance subtraction, that split makes multi-step conversion slightly inefficient for Physical damage (see the armor article).

% bonuses follow the destination type

This one rule reshapes how you gear and devote a conversion build.

• ▸Global % damage bonuses - from gear, devotions, passives - apply based on the destination type. Fire %, not Physical %, grows damage converted from Physical to Fire.
• ▸The % bonuses granted by Cunning and Spirit also follow the destination type: under Physical-to-Fire conversion, that damage scales with Spirit, not Cunning (see the attributes article).
• ▸So at 100% conversion, the original type's global % bonuses stop contributing to that skill - prioritize the destination type's % when upgrading gear.
• ▸Enemy resistances also check the destination type: a 100% Physical-to-Fire skill is mitigated by the enemy's Fire resistance, not Physical.
• ▸Skill-tree-local % bonuses behave in a more complex way - they are converted along with the damage and only apply to instances generated in the same step. The Japanese wiki's Combat Mechanics page walks through worked examples; for everyday build play, 'in-tree % roughly follows the conversion' is a sufficient mental model.

Advanced notes: Elemental conversion and priority

• ▸'Elemental' conversions come in two types: single-type lines like 'Cold to Acid', and grouped lines like 'Elemental to Vitality' that cover Fire, Cold, and Lightning together. The two never add together - they process as separate steps.
• ▸Under a 'Physical to Elemental' conversion, converted damage splits one third each into Fire, Cold, and Lightning; the reverse direction converts the same percentage from each of the three types.
• ▸The order between single-type and grouped Elemental conversion is not fixed - it follows source priority. For global conversion that priority is buff skills over gear, and within gear main hand over off hand over amulet, and so on. Whichever conversion processes first claims the larger share, so swapping the order changes the distribution - in the wiki's worked example, reversing the priority of 'Cold to Acid' and 'Elemental to Vitality' swaps the Acid and Vitality amounts.
• ▸Local conversion follows a separate priority rule: on v1.2.1.6, right after session start it runs mastery skills first, then head, amulet, medal, main hand, off hand - and swapping equipment mid-session gives priority to whichever item's modifier was equipped first. This behavior is announced to change in v1.3.0.0 (this article is verified against v1.2.1.6) - builds that depend on this corner should re-check the patch notes.
• ▸To verify a conversion breakdown yourself, rebuild the setup in the Grim Tools build calculator and compare the numbers (see the Grim Tools article in the related links).

1. Grim Dawn Japanese Wiki: Combat Mechanics — Confirms the three-step processing (local, global, armor piercing; no re-conversion), same-step additivity with the 100% cap, proportional splitting, % bonuses following the destination type, the two Elemental conversion types and their priority, DoT conversion conditions, and the announced v1.3.0.0 change to local-conversion rules.
2. Official Grim Dawn Game Guide: Combat — Confirms the official basics of flat damage, % bonuses, and the armor calculation the conversion rules interact with.
3. Official Crate Forum: Grim Dawn v1.2.1.6 + Hotfix — Official patch notes for the verified version.
4. Official Crate Forum: v1.3.0 Playtest Changelog — Reference for upcoming conversion-related changes (this article is verified against v1.2.1.6).