Accuracy is a percentile measurement of a player's ability to hit hit objects on-time. There are three types of accuracy that a player can have: the beatmap's accuracy, which is dependent on hit scores gained; the player's overall accuracy, which is weighed to allow better scores to stand out more; and the player's Performance Points (pp) accuracy, which is dependent on the submitted score's accuracy.
Accuracy formula for osu!standard
In osu!standard, accuracy is calculated by weighting the judgement gained from each hit object by its value and divided by the maximum possible amount.
Reference for one hit circle:
300 -> 300 / 300 = 1 = 100.00% 100 -> 100 / 300 = 1/3 = 33.33% 50 -> 50 / 300 = 1/6 = 16.67% 0 -> 0 / 300 = 0 = 0.00%
Accuracy formula for osu!taiko
In osu!taiko, accuracy is calculated by taking the sum of the note accuracy (how close you were to hitting the note on-time) divided by the number of total notes scored thus far. The note accuracies are labeled as a GREAT (良) (counts as 100%), GOOD (可) (counts as 50%) (half), and MISS/BAD (不可) (counts as 0%, which also breaks the combo). Drum rolls and spinners do not influence accuracy.
Accuracy formula for osu!catch
In osu!catch, accuracy is calculated by taking the total number of non-spinner hit objects collected, divided by the total number of non-spinner objects. All hit objects have the same value; except for bananas, as they are part of the spinner objects.
Note for API users: To calculate the accuracy in osu!catch, the number of droplets are under
count50 and the number of missed droplets are under
Accuracy formula for osu!mania
In osu!mania, accuracy is calculated similarly to osu!standard.
The performance graph is a chart that displays the player's performance (based on their life bar) over the course of a play (time). Additional information can be shown when hovering the in-game cursor over it.
Note: The additional information can only be viewed after playing a beatmap or watching a replay. After exiting the results screen, this information will not be saved.
When hovering over the performance graph, a tooltip is displayed with an
Unstable Rate rating.
Due to the way the DT (Double Time) and HT (Half Time) mods are implemented, the error and unstable rate values will be multiplied by the same factor as the song. To get the true values when playing with the DT mod, divide the results by 1.5. Similarly, multiply the results by 1.33 when playing with the HT mod.
Error will always display two values that represents how far off the early hits were on average and how far off the late hits were on average. The higher the Overall Difficulty value of the beatmap is, the lower the error values will have to be to do well when playing the beatmap.
Unstable Rate represents the consistency of the timing of the hits, where lower numbers are better (top players often score below 100). Note that the value measures consistency, not accuracy, so consistently hitting 15ms early is the same as consistently hitting on-time. The formula is essentially the standard deviation of the hit errors (in milliseconds), multiplied by 10. Sample code is available as reference, showing how osu-stable calculates the unstable rate values.
Note: Spin is only used for osu!standard.
In addition to the accuracy, some information regarding spinners is also seen in the same tooltip.
Speed represents the average RPM (revolutions per minute) on all the spinners in the beatmap.
Max is the highest RPM the player achieved in any of the beatmap's spinners.