Gaming math lab · Timing · Original calculator
Cooldown reduction vs haste calculator
On this page
Percentage cooldown reduction subtracts a fraction of the base cooldown. Haste in this model increases recharge speed, so it divides the base cooldown by 1 + haste/100.
Generic mathematical model, not a named game’s simulator. All starting values are invented examples. Supply verified values for your game and check the assumptions below.
Your scenario
Formula and units
Reduction cooldown = base × (1 − reduction/100). Haste cooldown = base / (1 + haste/100). Uses = floor(window / cooldown) + 1, including a use at time zero and at the endpoint.
Worked example
A ten-second base cooldown becomes eight seconds at 20% reduction, but about 8.333 seconds at 20 haste. Over a sixty-second window, with an immediate opening use, these models allow eight uses each. An identical use count can hide different timing.
How to use this comparison
Set the base duration and the window relevant to your comparison. The equivalent-haste output converts the selected reduction to a speed increase producing the same cooldown. It does not imply that the game offers that amount of haste or uses this terminology.
Read the result correctly
Shorter cooldown does not automatically create one more use in a short encounter. Look at the use-count column as well as the duration. Opening availability matters: if the ability starts unavailable, subtract the time-zero assumption before applying these results.
Model boundaries
These are separate mathematical models, not rules attributed to a named game. They are not combined. There is no cast time, resource requirement, charge storage, cooldown floor, reset, cooldown-on-hit mechanic or global cooldown. Uses at the exact end of the window are counted.
Method: original arithmetic implementation and editorial examples reviewed October 16, 2026. Outputs follow the displayed formula and your inputs. We have not tested these mechanics inside a particular game.