Attack speed

Attack Speed (often shortened as AS or ASPD) is the frequency at which a champion performs basic attacks, also displayed as "attacks per second". Increases attack by additional adding a percentage of a champion's base attack speed. Champions with low base attack speed will benefit less from increased attack speed than champions with high base rate of attack. No champion can have more than 2.5 attacks per second, or 1 attack every two fifth of a second. The attack speed time can be increased and reduced with items, runes, masteries, and abilities.

Formula
To accurately calculate Attack Speed (AS), use the following formula:

AS = ASL1*(1+PB) + (AL)*(Lvl-1)

Variables:
 * AS: Total Attack Speed
 * ASL1: Attack Speed at Level 1
 * PB: AS% Bonus gained from Items/Abilities/Masteries/Runes
 * AL: Character's numerical AS increase per Level
 * Lvl: Current level

However, the League of Legends Wiki currently displays AS increase per level as a percentage for easier calculation. Here is the simplified formula.

AS = ASL1*(1+PB+[%AL*(Lvl-1)])

%AL: Character's percentage AS increase per level.


 * Note: Percentages have been rounded, so results using this equation may be slightly different than actual values in gameplay.

Items

 * : +25% Attack Speed, UNIQUE Passive: Enhanced Movement 2. 920 Gold
 * : +15% Attack Speed. 420 Gold
 * : +35 Attack Damage, +45 Ability Power, Passive: On attack, increases your Attack Speed by 4% and Ability Power by 6. Lasts 5 seconds (stacks up to 8 times). 2235 Gold
 * : +35 Attack Damage, +40% Attack Speed, +30 Armor UNIQUE - On hit, deals Magic Damage equal to 4% of the target's maximum Health. 3800 Gold
 * : +50% Attack Speed, +25 Ability Power UNIQUE Passive: Your physical attacks shred your target doing 20 magic damage and reducing their magic resistance by 6. Stacks 4 times. 1825 Gold
 * : +50% Attack Speed, +55 Ability Power, +10 Mana Regeneration (per 5) UNIQUE Passive: Reduces ability cooldowns by 25%. 2885 Gold
 * : +55% Attack Speed, +30% Critical Chance, +15% Movement Speed. 2895 Gold
 * : +40% Attack Speed. 1050 Gold
 * : +20% Attack Speed, UNIQUE Aura: Gives nearby allied Champions 20% Lifesteal, 20% Attack Speed, and 30 Health per 5 seconds regenerated. Reduces the armor of nearby enemy champions by 20. 2550 Gold
 * : +40% Attack Speed UNIQUE Passive: Reduces ability cooldowns by 10%. 1140 Gold
 * : +60% Attack Speed UNIQUE Passive: Every fourth attack deals 100 extra Magic Damage, UNIQUE Active: Your attacks cannot be dodged and you gain 30 Armor Penetration for 8 sec. (40 second cooldown). 1970 Gold
 * +30% Attack Speed, +55 Damage. Passive: Physical attacks reduce your target's Armor by 15 for 5 seconds, (maximum 3 stacks). 3065 Gold
 * : +30 Damage, +30 Ability Power, +30% Attack Speed, +15% Crit Chance, +12% Move Speed, +250 Health, +250 Mana, UNIQUE Passive: 25% chance on hit to slow the target by 35% for 2.5 seconds; on cast, increases your base Attack Damage by 150% for one attack. 4070 Gold
 * : +40% Attack Speed, +32 Magic Resist, Passive: Physical attacks remove up to 42 mana from the target and deal additional damage equal to the amount of mana removed. 2150 Gold
 * : +30 Attack Damage, +15% Critical Chance UNIQUE Passive: Gives 20 Armor Penetration and 15% Cooldown Reduction, UNIQUE Active: Gives 20% movement speed and +50% attack speed for 4 seconds. Attacking enemy units with melee attacks increases the duration by 2 to a maximum of 8 seconds. 60 second cooldown. 2687 Gold
 * : +20% Attack Speed, +10% Critical Chance, +8% Movement Speed. 1195 Gold

Consumable

 * : +12-22% Attack Speed, based on champion level, and 8% Critical Chance for 4 minutes. 250 Gold

Champion Abilities

 * increases his attack speed by 30/38/46/54/62% for 8 seconds.
 * increases her attack speed by 50/75/100% for 10 seconds.
 * increases his attack speed by 15% for 6 seconds when he hits a target with any of his abilities (stackable up to 5 times).
 * increases the attack speed of allied champions it passes through by 20/25/30/35/40% for 5 seconds.
 * causes his basic attacks to increase his attack speed by 6/10/14% for 2.5 seconds (stackable up to 10 times).
 * increases his attack speed by 10/15/20/25/30%.
 * 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 an allied unit's attack speed by 20/30/40/50/60% for 7 seconds.
 * increases an allied unit's and his own attack speed by 25/35/45/55/65% for 15 seconds.
 * increases his attack speed by 1% per 1% health missing.
 * increases his attack speed by 35/50/65% for 25 seconds.
 * increases his attack speed by 50% for 20 seconds.
 * increases her attack speed by 30/60/90% and one third of that to nearby allies for 15 seconds.
 * increases his attack speed by 40% for 3 seconds when he attacks while stealthed.
 * increases her attack speed by 30/45/60/75/90% for 7 seconds.
 * 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% for 5 seconds upon switching stances (stackable up to 3 times).
 * increases his attack speed by 20/25/30/35/40%, and for additional 15/20/25/30/35% for 5 secs on activation.
 * increases his attack speed by 40/50/60/70/80% and half of that to nearby allied champions for 10 seconds.
 * increases his attack speed by 15/20/25/30/35%. 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 attack speed and ability power by 1.33/2.67/4%.

Runes

 * Alacrity runes increase attack speed.

Neutral Buffs

 * The Crest of Nature's Fury buff gives 20% increased attack speed.

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 25% for 3 seconds.
 * : UNIQUE Active: Slows movement speeds and attack speeds of surrounding units by 35% for 1 second + 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

 * slows affected units' attack speed by 20% for 1 seconds.
 * 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 30/35/40/45/50% 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.

Final Notes

 * All percentages listed in a character's Attack Speed statistic are approximations.