Cooldown Reduction (CDR) refers to the shortening of the time that a skill can be used again or chargers on a skill are available again.
Which items can have Cooldown Reductions
Not so many as it turns out. However much of your CDR can come from skills both active and passive as well as Glyphs, Legendary Aspects and Unique items.
| Attribute | Amulet | Helm | Legs | Gloves | Off-Hand | Shield |
|---|---|---|---|---|---|---|
| Cooldown Reduction [4.2% - 7%] |
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| Cooldown Reduction [7%] |
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| Druid: Storm Skills CDR [4.2 - 7%] |
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| Rogue: Trap Skills CDR [4.2 - 7%] |
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| Rogue: Imbuement Skills CDR [10.5 - 17.5%] |
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| Attribute | Amulet | Helm | Legs | Gloves | Off-Hand | Shield |
How Cooldown Reductions are Calculated
Cooldown Reduction is multiplicative. For example
Your skill has a 30 second cooldown. You are wearing:
- Helm: 6% cooldown reduction
- Amulet: 4% cooldown reduction
- Offhand: 7% cooldown reduction
You don't just add these percentages together.
Subtract each reduction percentage from 100% (because you want to know how much is left after the reduction):
- Helm: 100% - 6% = 94%
- Amulet: 100% - 4% = 96%
- Offhand: 100% - 7% = 93%
Multiply these percentages together:
- 0.94 × 0.96 × 0.93 = 0.839904
Subtract that result from 1 to find the total reduction:
- 1 - 0.839904 = 0.160768 x 100 = 16%
So the final reduction on a 30-second cooldown is 4.8 seconds meaning your skill has a new cooldown of 25.2 seconds.