Attack Speed

The frequency with which units attack is measured in attack speed. A unit's attack speed can be increased by items, agility, buffs from abilities, auras and passive abilities. Attack speed is capped at 400 and -80.

Base attack time
Every unit has a base attack time (BAT). It is the interval in seconds between each attack. This base value cannot change (except by certain Hero transformation abilities, such as Alchemist's Chemical Rage), but what can change is the unit's increased attack speed.

All Heroes have a BAT of 1.7 except for the following:


 * Alchemist (under Chemical Rage): BAT 1.4/1.2/1.0
 * Anti-Mage: BAT 1.45
 * Huskar: BAT 1.6
 * Juggernaut: BAT 1.6
 * Lone Druid (under True Form): BAT 1.6
 * Lycanthrope (under Shapeshift): BAT 1.5
 * Soul Keeper: BAT 1.5
 * Troll Warlord (under Berserker Rage): BAT 1.55
 * Treant Protector: BAT 1.9
 * Windrunner: BAT 1.5

Increased attack speed
Increased attack speed (IAS) gives you a percentage of your base attack speed (or attack per second). It works together with base attack time to determine how often a unit can attack. As it is a percentage bonus, attack speed increases linearly, and doubles at 100 IAS, maxing out at 400 (5x attack speed). IAS cannot fall below the value of -80 (attack speed divided by 5).

Attack speed formula
To determine how often a unit attacks, the formula below is used:


 * Attack Time = BAT / (1 + IAS)
 * Attacks per Second = (1 + IAS) / BAT

IAS is a percentage, so you must divide your actual IAS by 100 before using it in this formula. IAS reduces a percentage of your BAT, thus giving you a corresponding percentage of attack per second as follow: +1 IAS equals +1% of your attack speed.

For example: +100 IAS = +100% attack per second, meaning your attack speed doubles or BAT reduced by half.

List of Items that give Increased Attack Speed
* Item provides increased attack speed exclusively via Agility.