Cooldown Reduction (abbreviated as CDR) is a champion statistic that reduces the cooldown of abilities, or the amount of time before an ability can be used again after activation, by a percentage. There are some items that separately reduce the cooldown for summoner spells or item active abilities, but do not grant cooldown reduction.

Cooldown reduction can be granted by items, Crest of Insight buffs, and runes. CDR stacks additively and is capped at 40%, which can be increased to 45% with the Cosmic Insight Cosmic Insight rune.

Cooldown reduction is determined at the moment an ability is activated. Increasing/decreasing cooldown reduction while the skill is on cooldown will not affect the cooldown.

Cooldown reduction does not apply to:

Although not a basic item, Fiendish Codex Fiendish Codex is the item from which the cooldown reduction gold value of Gold.png 24.75 per % cooldown reduction is derived.

Increasing cooldown reduction


Item Cost Amount Availability
Morellonomicon Morellonomicon2900 Gold.png 20 % (Unique)Common
  • Essence Reaver Essence Reaver: Passive: Unique: Gain 0% - 20% (in base al critical strike chance) additional cooldown reduction. This bonus does not include the critical strike chance given by this item.


Champion abilities

Some champions have abilities that decrease their cooldowns by a flat amount, either their base cooldown or current cooldown, or entirely refresh their cooldown. Base reduction occurs before cooldown reduction takes effect while flat reduction occurs after cooldown reduction takes effect. By using those, a champion can circumvent the 40% cooldown reduction cap.

  • Depending on built-in reduction type:
    • Base (applies before CDR)
    • Flat (applies after CDR)
    • Percent (applies to base / current / total cooldown)
    • Refresh (cooldown is immediately reduced to 0)

Base reduction

Flat reduction

Percentage reduction

Cooldown refreshing

Other cooldown reducing effects

Active ability items

Active Item CDR Perfect Timing Perfect Timing
None 15%
24xpx 5% 19.25%
24px0 10% 23.5%
24px024xpx 15% 27.75%
24px1 16% 28.6%
24px124xpx 21% 32.85%
24px2 22% 33.7%
24px224xpx 27% 41.6%
24px3 28% 38.8%
24px324xpx 33% 43.05%
24px4 34% 43.9%
24px424xpx 39% 48.15%
24px5 40% 49%
24px524xpx 45% 53.25%

Summoner spells

Summoner spell CDR
Base cooldown ▶ 300s
Cooldown reduction icon.png Cooldown reduction
5% (20xpx) 285s 228s 199.5s 171s 71.75s N/A
10% (20xpx) 270s 216s 189s 162s 67.5s N/A
15% (20xpx20xpx) 255s 204s 178.5s 153s 63.25s N/A
25% (20xpx) 225s 180s 157.5s 135s 56.25s N/A
30% (20xpx20xpx) 210s 168s 147s 126s 52.5s N/A
35% (20xpx20xpx) 195s 156s 136.5s 117s 48.75s N/A
40% (20xpx20xpx20xpx) 180s 144s 126s 108s 45s N/A
40% (20px) 180s 144s 126s 108s N/A 48s
43% (20px20xpx) 171s 136.8s 119.7s 102.6s N/A 45.6s
50% (20px20xpx) 150s 120s 105s 90s N/A 40s
52.5% (20px20xpx20xpx) 142.5s 114s 99.75s 85.5s N/A 38s
55% (20px20xpx) 135s 108s 94.5s 81s N/A 36s
58% (20px20xpx20xpx) 126s 100.8s 88.2s 75.6s N/A 33.6s
65% (20px20xpx20xpx) 105s 84s 73.5s 63s N/A 28s
68% (20px20xpx20xpx20xpx) 96s 76.8s 67.2s 57.6s N/A 25.6s


Last updated: November 21, 2017 – V7.23

One cost and efficient way to reach maximum CDR (45%) is:

The most cooldown reduction any champion can obtain at level 1 with Gold.png 500 is 20%. To achieve this you must :

Relevant mathematics:
5% + 5% + 10%  = 20%
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