Cooldown Reduction Calculator

Cooldown Reduction (CDR) in video games reduces the wait time between uses of abilities or skills. Most games apply CDR using a multiplicative formula — which means each additional point of CDR is worth less than the last (diminishing returns).

Standard multiplicative CDR formula: Effective Cooldown = Base Cooldown × (1 − CDR%/100)

Additive CDR (some games stack differently): Effective Cooldown = Base Cooldown ÷ (1 + CDR%/100) Note: Additive CDR provides increasing returns — each additional point gives you more casts per minute.

Casts per minute formula: Casts Per Minute = 60 ÷ Effective Cooldown

What each variable means:

• Base Cooldown: the ability’s reset timer before any reduction (in seconds).
• CDR%: the total Cooldown Reduction percentage from items, talents, buffs, or character stats.
• Effective Cooldown: the actual time you wait between casts after CDR is applied.
• Casts Per Minute (CPM): how many times you can use the ability per minute; a key DPS metric.

Worked example (League of Legends style): Ability base cooldown: 12 seconds. You have 30% CDR from items. Effective CD = 12 × (1 − 0.30) = 12 × 0.70 = 8.4 seconds Casts per minute = 60 ÷ 8.4 = 7.14 casts/min vs. 60 ÷ 12 = 5.0 without CDR.

Diminishing returns illustration:

• 0% → 10% CDR: 12s → 10.8s (saves 1.2s per cast)
• 30% → 40% CDR: 8.4s → 7.2s (saves 1.2s per cast) Wait — multiplicative CDR is actually linear in cooldown seconds! But in terms of additional CDR items: going from 30% to 40% costs the same item slots but provides fewer extra casts per minute than going from 0% to 10% did proportionally.

Hard caps: Many games cap CDR at 40–50% (e.g., old League of Legends cap was 40%, now Ability Haste uses an alternative formula). Always check your specific game’s mechanics.