Formula Used
The calculator first adds every haste source.
Total Ability Haste = Current Haste + Item Haste + Rune Haste + Buff Haste + Temporary Haste
Then it converts ability haste into cooldown.
Cooldown After Haste = Base Cooldown × 100 ÷ (100 + Total Ability Haste)
If a refund is entered, the calculator applies it after the haste result.
Final Cooldown = Cooldown After Haste × (1 - Refund Percent ÷ 100)
Cast count assumes the first cast happens after the entered delay.
Casts = floor((Fight Window - First Cast Delay) ÷ Final Cooldown) + 1
How To Use This Calculator
Enter the champion and ability name for your own record.
Add the base cooldown from the ability tooltip.
Enter haste from items, runes, buffs, and temporary effects.
Use cooldown refund percent only for effects that reduce the timer.
Add the expected fight window in seconds.
Press Calculate to view the result above the form.
Use CSV for spreadsheet storage.
Use PDF for a quick saved report.
Why Ability Haste Matters
Ability haste is a scaling cooldown stat. It does not stack like old cooldown reduction. Each point gives one percent more spell casts over a long period. That means thirty haste gives about twenty three percent cooldown reduction, not thirty percent. This calculator helps you see that curve before you lock a build. It also shows how many casts fit inside a trade, skirmish, or full team fight.
Planning Around Real Fight Windows
League fights rarely last forever. A champion may only get six seconds near a target. Another may poke for thirty seconds before objective control begins. Because of that, final cooldown is only part of the answer. Cast count often matters more. One small haste purchase can add a complete extra spell when the window crosses a timing threshold. That extra cast can decide burst damage, shields, crowd control, or wave clear.
Building Better Item Comparisons
Use separate fields for item, rune, buff, and temporary haste. This keeps the build readable. It also makes exported results easier to compare later. Enter a target cooldown when you need a specific rotation. For example, a mage may want a control spell below four seconds. A support may want a shield ready before the next engage. The required haste estimate shows whether that target is realistic.
Reading The Output
The effective reduction percent explains how much the base timer shrinks. The final cooldown shows the practical wait between casts. Uses per minute is useful for farming and poke patterns. Casts inside the fight window shows immediate combat value. Extra casts versus zero haste highlights the real gain. Time saved per reuse helps compare haste with raw damage, mana, and survivability.
Use It With Game Sense
No calculator can know every reset, animation, silence, stun, or cooldown refund. Treat results as planning numbers. Review your champion kit after every patch. Combine these results with matchup knowledge and objective timers. Haste is strongest when it creates one more meaningful cast. It is weaker when mana, range, or safety stops you from using that spell on time.
Save exports for common champions. Compare new builds when items or runes change later. Keep notes beside matchup plans during testing sessions too.
FAQs
What does ability haste do?
Ability haste increases how often abilities can be cast. It reduces the effective cooldown using a scaling formula, not a flat percentage system.
Is 100 ability haste equal to 100% cooldown reduction?
No. One hundred ability haste means the ability can be cast twice as often. That equals fifty percent cooldown reduction.
Why is cooldown reduction not the same as haste?
Cooldown reduction used a direct percentage. Ability haste scales by cast frequency. This avoids old hard caps and makes each haste point useful.
Can I include item and rune haste together?
Yes. Enter item haste and rune haste in separate fields. The calculator adds them into one total ability haste value.
What is fight window duration?
Fight window duration is the time you expect to cast during a trade, skirmish, objective fight, or team fight.
What does first cast delay mean?
First cast delay is the time before your first ability use. Use zero when the ability is cast immediately as the fight starts.
When should I use cooldown refund percent?
Use it when a spell, item, passive, or reset effect returns part of the cooldown after casting or hitting a condition.
Can this predict every real match result?
No. Real matches include movement, stuns, silences, range limits, mana limits, and missed casts. Use it as a planning tool.