For suggested AR values, see: Ranking criteria
Approach rate (AR) is a beatmap difficulty setting that defines when hit objects start to fade in relative to when they should be hit or collected. It exists only in osu! and osu!catch.
AR values range from 0 to 10. Higher approach rates mean that hit objects will be shown for a shorter period of time, giving less time for a player to react. On the other hand, lower approach rates allow more reaction time, but can result in an overwhelming amount of hit objects appearing on the screen at once.
The duration of a hit object that stays visible on the screen (without mods) ranges from 1800ms at AR0 to 450ms at AR10. AR levels scale by 120ms for below AR5 and 150ms for above AR5.
See the infographic and formulas below for an overview:
X = hit/collect
p r e e m p t ↓
├───────────────────────┬──────────────┤
0% fade_in 100% opacity
The hit object starts fading in at X - preempt with:
preempt = 1200ms + 600ms * (5 - AR) / 5
preempt = 1200ms
preempt = 1200ms - 750ms * (AR - 5) / 5
The amount of time it takes for the hit object to completely fade in is also reliant on the approach rate:
fade_in = 800ms + 400ms * (5 - AR) / 5
fade_in = 800ms
fade_in = 800ms - 500ms * (AR - 5) / 5
There are four mods that alter the approach rate when activated:
While Half Time and Double Time do not change the AR value, the speed difference leads to an apparent AR change. HT/DT ARs are commonly referred to in terms of their perceived value. For example, "AR8+DT" may also be written as "AR9.6".
Approach rate is visible when viewing osu!taiko or osu!mania beatmap information, but it does not affect gameplay. Each mode's scroll speed is determined by other factors.