Attack speed

Attack Speed (often shortened as AS or ASPD) is the frequency of a champion's basic attacks. They are measured and displayed as attacks per second.
 * Attack speed cannot be increased beyond attacks per second (or 1 attack every two fifths of a second, or  seconds).

Attack speed bonuses (from items or abilities, etc.) are in percent. The bonus is a percentage of the champions base attack speed. Therefore, champions with higher base attack speed benefit more from attack speed increases. Like all stats, one's attack speed can be increased via leveling up, items, runes, buffs, and abilities. Some items and abilities (only those two) decrease enemy attack speed.

Base attack speed
Every champion's base attack speed (ASbase) is calculated using a hidden variable called attack delay, which ranges from &minus; to. As ASbase is the value that is modified by bonus attack speed, and the amount shown at level 1 for most champions (excepting those with bonus attack speed at level 1), it is the value shown on the League of Legends Wiki.

$$\pagecolor{Black}\color{White}{\it AS}_{\rm base} = {0.625 \over 1 + {\it attack\ delay}}$$

Bonus attack speed sources

 * Champions gain an attack speed percentage every time they level up, which ranges from roughly 0 - 6% (the exact number depending on the specific champion) and can be calculated through the statistics growth formula.
 * Items
 * Champion abilities
 * Runes

Bonus AS% stacks additively.


 * Example: grants +35% attack speed and  also grants +50% attack speed, so the champion gains +85% in total.

Notes:
 * Final attack speed cannot go above the cap of  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.

Example

 * Calculating base attack speed:
 * attack delay is &minus;0.04.
 * $$\pagecolor{Black}\color{White}{0.625 \over (1 - 0.04)} = {0.625 \over 0.96} = 0.651041 \overline{6}$$. This is base attack speed, seen at level 1 (without runes, etc.).
 * The number seen in game is rounded to 3 decimal places: 0.651.
 * Calculating "bonus attack speed":
 * Every time levels up, he gains bonus AS% based on percentage growth 3.22% and his level through the statistics growth formula.
 * At level 18 he has gained $$\pagecolor{Black}\color{White}3.22\% \times\left({7 \over 400}\times(18^2-1)+{267\over400}\times(18-1)\right)=54.74\%$$ as bonus AS%.
 * At 18 he has maxed increasing his attack speed by 30%.
 * Let's say he has the mastery up to 4%.
 * Let's also say he has : +35%.
 * All together he has: 54.74% + 30% + 4% + 35% = 123.74% bonus AS% or bonus AS as a decimal.
 * Final calculation:
 * $$\pagecolor{Black}\color{White}\begin{align} & {0.625 \over 0.96} + \left({{0.625 \over 0.96} \times 123.74\%}\right) \\ =& 0.651041\overline6 + ({0.651041 \times 123.74\%}) \\ \approx & 1.45664 \end{align}$$
 * In game, the number will be shown as: 1.457.

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.

Reducing 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.

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 enemy champion's attack speed by 50% for 1. 5 seconds.
 * slows affected units' attack speed by for 3 seconds.
 * reduces an enemy unit's attack speed by plus an additional  per second for 5 seconds, for a total of.
 * reduces an enemy unit's attack speed by 25% for 3 seconds.
 * slows the attack speed of all nearby enemy units by 25% while channeling for 3 seconds.

Trivia
Last updated: October 11, 2016 – V6.20
 * The most attack speed a champion can reach at level 1 with the initial is  with.
 * Base AS: 
 * Bonus AS: 
 * Buffs: 
 * (+25% AS)
 * (+25% AS)
 * (+20% AS)
 * (+20% AS)
 * Runes: 
 * 9 (+9% AS)
 * 9 (+9% AS)
 * 9 (+9% AS)
 * 3 (+3% AS)
 * Item: 
 * One (+12% AS)
 * Masteries: 
 * 5 points in (+4% AS)
 * AS Amplification: 
 * (+100% total AS)
 * Relevant mathematics:
 * total AS:
 * Buffs
 * Runes
 * bonus AS90%%
 * total AS