Attack delay, also known as attack speed offset, was a hidden variable that was used to calculate a champion's "base attack speed." The formula for this calculation was as follows:

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

This value is rounded at 3 decimals for in-game calculations.

A negative attack delay corresponded to a higher base attack speed (i.e. attacks per second), which consequently made bonus attack speed more effective.

Contrary to popular believe, attack delay was not responsible for how "good" an attack feels. A number of other hidden variables were used to determine when an attack wind-up is considered complete as well as when an attack is considered to have hit - e.g. some projectile-based attackers can click to move the moment the projectile is airborne, whereas others may "cancel" the attack at any point prior to the projectile hitting. These variables were not viewable/accessible.

Attack delay stopped being used by Riot Games Inc. at the end of Season Eight on patch V8.21.

Examples of attack delay and base attack speed:

  • Standard base attack speed
    • Attack delay: 0
    • Decimal: 0.625
    • Precise fraction: 0.625 ÷ 1
  • Low base attack speed
    • Attack delay: 0.3
    • Decimal: 0.481
    • Precise fraction: 0.625 ÷ 1.3
  • High base attack speed
    • Attack delay: -0.1
    • Decimal: 0.694
    • Precise fraction: 0.625 ÷ 0.9