Attack speed

Attack speed (often shortened as AS or ASPD) is the frequency at which a champion performs basic attacks and are displayed as "attacks per second". Attack speed caps at 2.5 attacks per second, or 1 attack every two fifths of a second.

Attack speed bonuses works by adding a percentage of a champion's base attack speed to his or her "base attack speed". Champions with low base attack speed will benefit less from increased attack speed than champions with high base rate of attack. One's attack speed can be increased via leveling up, items, runes, masteries, buffs, and abilities. One's attack speed can only be decreased by items, abilities, and the.

Base attack speed
Every champion's "base attack speed" (ASbase) is calculated using a hidden variable called "attack delay". Attack delay is a number (up to 2 decimal places) between -0.1 and +0.08:

ASbase = 0.625 / (1 + attack_delay)

This value is the the total number shown at level 1 without runes, masteries, etc. It is represented this way throughout the wiki.

Final attack speed
Attack Speed (AS) is then calculated using the following formula:

AS = ASbase &times; (100% + bonus_AS%)

The bonus AS% can come from 6 sources:
 * Every time a champion levels up, bonus AS% is added (between 1.00% to 4.00%, up to 2 decimal places, depending on the champion). (This is the growth shown on the wiki champion's pages).
 * Items.
 * Champion abilities.
 * Masteries: and.
 * Runes:.
 * The buff.

All bonus AS% is additive, except for the mastery, which multiplies bonus attack speed. This means that you receive no benefit from it if you don't have any other bonus attack speed.

For example:
 * 40%  + : 50% = 90% bonus AS
 * (: 40% + : 50%) &times; : 104% = 93.6% bonus AS

Notes:


 * Final attack speed cannot go above the cap of 2.5 attacks per second.


 * Many in-game tooltip percentages (such as runes) have been rounded, so results may be slightly different unless the precise numbers are known.

Calculation Example
 * Calculating "base attack speed":
 * attack_delay = -0.04.
 * 0.625 / (1 &minus; 0.04) = 0.625 / 0.96 = 0.651041 6 . This is base attack speed, seen at level 1 (without runes, masteries, etc).
 * The number seen in game is rounded to 3 decimal places: 0.651.
 * Calculating "bonus attack speed":
 * Every time levels up, he gains 3.22% as bonus AS%.
 * At level 18 (after leveling up 17 times) he has gained 3.22% &times; 17 = 54.74% as bonus AS%.
 * At 18 he has maxed increasing his attack speed by 15%.
 * Let's say he has the mastery up to 4%.
 * Let's also say he has : +55% and : +60%.
 * All together he has: 54.74 + 15 + 4 + 55 + 60 = 188.74% as bonus AS%.
 * But he also has mastery up to 4%. So all the bonus AS% is multiplied by 104%.
 * 188.74% &times; 104% = 196.29.
 * Final calculation:
 * (0.625 / 0.96) &times; (100% + 196.29%).
 * 0.651041 6 &times; 296.29% = 1.9289713541 6.
 * In game, the rounded number will be shown as: 1.929.

Attack Speed Listing
Here is a table listing the items that give attack speed, their gold cost, and how much attack speed you get for your gold. Items where attack speed is gained from a stackable buff, such as Guinsoo's Rageblade, are listed twice: once at 1 buff stack and once at max stack.

We can see that Elixir of Agility provides the best attack speed per gold, at all levels. The Recurve Bow and Dagger both give great attack speed for their gold, but they have no other bonuses so I wouldn't recommend stacking them.

Champion abilities
Note: Only the attack speed buff effect of these abilities is shown here, to read more information on each of these abilities, follow the link on each of them.
 * increases his attack speed by 30 / 38 / 46 / 54 / 62 % for 8 seconds.
 * increases her attack speed by 25 / 50 / 75 % for 10 seconds.
 * passively increases his attack speed by 10 % whenever he hits a target with any of his abilities. This bonus lasts for 6 seconds and stacks up to 5 times.
 * increases the attack speed of allied champions it passes through by 20 / 25 / 30 / 35 / 40 % for 5 seconds.
 * increases his attack speed by 40 / 50 / 60 / 70 / 80 % for 4 seconds.
 * passively increases his attack speed by 10 / 13 / 16 / 19 / 22 %. When activated, it throws a flag that increases nearby allied champions and his own attack speed again by the same amount.
 * causes his basic attacks to increase his attack speed by 6 / 10 / 14 %. This bonus lasts for 2.5 seconds and stacks up to ten times.
 * reduces magic damage taken by 15 % and transforms this damage into bonus attack speed. This effect stacks individually and each individual buff lasts up to 4 seconds.
 * passively increases his attack speed by 10 / 15 / 20 / 25 / 30 %.
 * increases the attack speed by 50 % of his next two 2 autoattacks within the next three seconds after casting an ability.
 * increases his attack speed by 40 / 60 / 80% for 6 / 9 / 12 seconds.
 * increases her attack speed by 30 / 35 / 40 / 45 / 50 % for 6 seconds.
 * increases her or an allied unit's attack speed by 20 / 30 / 40 / 50 / 60 % for 7 seconds.
 * passively grants himself 20 / 25 / 30 / 35 / 40 % attack speed. Upon activation, it summons a spell shield for two seconds, if the shield successfully blocks a spell, the attack speed bonus is doubled for 5 seconds.
 * increases an allied unit's and his own attack speed by 25 / 35 / 45 / 55 / 65 % for 15 seconds.
 * passively increases his attack speed by 1 % per 1 % health he is missing.
 * increases his attack speed by 50 % for 20 seconds.
 * grants her an aura for 15 seconds that increases her attack speed by 30 / 60 / 90 % and one third of that to nearby allies.
 * grants him a shield for up to 6 seconds, while the shield persists Skarner increases his attack speed by 30 / 35 / 40 / 45 / 50 %.
 * increases his attack speed by 40 % for 3 seconds after leaving his stealth state.
 * increases her attack speed by 30 / 45 / 60 / 75 / 90 % for 7 seconds.
 * infects the target location for 8 seconds, while on this area, Trundle increases his attack speed by 20 / 30 / 40 / 50 / 60 %.
 * passively increases his attack speed by 3 / 6 / 9 / 12 / 15 %.
 * increases his attack speed by 30 / 40 / 50 / 60 / 70 % for up to 10 seconds depending on how long he was stealthed before attacking.
 * increases his attack speed by 10 % upon switching stances. This bonus lasts for 5 seconds and stacks up to 3 times.
 * increases his attack speed by 20 / 25 / 30 / 35 / 40 % while the stance is active, and for additional 15 / 20 / 25 / 30 / 35 % for 5 seconds on activation.
 * increases his attack speed by 40 / 50 / 60 / 70 / 80 % and half of that amount to nearby allied champions for 10 seconds.
 * increases his attack speed by 20 / 25 / 30 / 35 / 40 % after hitting a target with this skill.
 * increases his attack speed by 20 / 25 / 30 / 35 / 40 %. He can activate this ability to double the effect for 7 seconds.

Masteries

 * increases your champion's attack speed by 1 / 2 / 3 / 4 %.
 * increases your champion's ability power and bonus attack speed by 1.33 / 2.66 / 4 %.

Runes

 * runes increase attack speed.

Neutral buffs

 * The buff increases your champion's attack speed by 20 %.

Decreasing attack speed
Note: Attack speed reductions stack multiplicatively, and take percentages off the final attack speed value after all bonus attack speed has been factored in.

Items

 * : Unique passive: Reduces the attack speed of nearby enemies by 20%.
 * : Unique passive: 20% chance on being hit to slow the attacker's movement and attack speeds by 35% for 3 seconds.
 * : Unique active: Slows movement speeds and attack speeds of surrounding units by 35% for 2 seconds + 0.5 seconds for each 100 Armor and Magic Resist. 60 second cooldown.
 * : Passive: 20% chance on being hit to slow the attacker's movement and attack speeds by 35% for 3 seconds.

Champion abilities
Note: Only the attack speed reduction effect of these abilities is shown here, to read more information on each of these abilities, follow the link on each of them.
 * slows affected units' attack speed by 20% for 1 second.
 * decreases the attack speed of enemy champions it passes through by 20 / 25 / 30 / 35 / 40 % for 5 seconds.
 * slows affected units' attack speed by 20 / 25 / 30 / 35 / 40 % for 3 seconds.
 * slows affected units' attack speed by 30 / 37.5 / 45 / 52.5 / 60 % for 4 seconds.
 * slows affected units' attack speed by 30 / 35 / 40 / 45 / 50 % for 4 seconds.
 * reduces an enemy unit's attack speed by 35% plus an additional 3 / 6 / 9 / 12 / 15 % per second for 5 seconds.
 * reduces an enemy unit's attack speed by 25% for 4 seconds.
 * slows the attack speed of all nearby enemy units by 25% while channeling for 3 seconds.

Neutral monsters

 * The attacks will slow the attacked champion's attack speed by 20% for 4 seconds.