osu! judgement system

Judgements

A judgement, or hit result, is the outcome of interacting with a hit object during its hit window. Score and accuracy are calculated based on which judgements are received.

These are commonly referred to by their score value (except for misses), i.e. a GREAT is usually called a "300" and so on.

Image	Name	Hit value	Accuracy	Max hit error (ms)
	GREAT	300	100%	80 - 6 × OD
	OK	100	33.33%	140 - 8 × OD
	MEH	50	16.67%	200 - 10 × OD
	MISS	0	0%	400

The hit window depends on the beatmap's overall difficulty (OD). A hit is then considered inside a hit window if hit error < max hit error, meaning the value listed is half of the hit window width.

The hit error is rounded and the max hit error values are truncated to the nearest integer, meaning the windows may be up to 1.5 ms shorter on both sides than what the formulas suggest.

Geki and Katu

The last hit object in a combo set may give a variant of the regular judgements depending on which ones were achieved in the combo. They give a bit more health than the regular ones.

Image	Name	Variant of	Requirement
	Geki (激)	GREAT	GREAT on all hit objects in a combo
	Katu or Katsu (喝)	GREAT	At least OK on all hit objects in a combo and a GREAT for the last one
	Katu or Katsu (喝)	OK	At least OK on all hit objects in a combo

This mechanic is in reference to Osu! Tatakae! Ouendan and Elite Beat Agents, the latter using the terms Elite Beat! and Beat! instead of Geki and Katsu.

Judgement mechanics

Hit circles

A hit circle is judged with a GREAT, OK, MEH, or MISS depending on how accurately it is hit. Hitting a circle before the MISS window has no effect (other than causing notelock), and not hitting a circle will cause a MISS after the MEH window passes.

Sliders

Sliders consist of multiple parts: the slider head, slider tail, slider ticks, and slider repeats. The slider as a whole is judged based on how many parts of the slider the player has hit, as outlined below:

The slider head only needs to be hit within the MEH hit window for a successful hit. However, if ScoreV2 is active, slider head accuracy is additionally accounted for, with the judgement received for the entire slider being limited to at most the one received for the slider head.

There are some additional quirks with how sliders influence combo:

• Tapping the slider head too early (before the MEH hit window), missing a slider tick, or missing a repeat does not incur a MISS, but will cause a combo break. The other slider parts can still be hit if a key is held down. This is colloquially referred to as a slider break.
• Missing the slider end does not incur a MISS, but will not increment combo.

Spinners

Each spinner has a set number of spins required to complete it. This number depends on the overall difficulty of the beatmap. Spinner rotation speed is calculated based on cursor velocity and does not necessarily correspond to how many times the cursor has revolved around the spinner.

The spin requirements can be broken down into the following formulas:

If a spinner is very short, the number of spins required may be calculated to be 0, and thus the spinner will always complete itself with a GREAT.

History

The spinner judgement algorithm has been significantly changed in the 20190513.2 Stable release. The differences were as follows:

• The difference between OK and MEH, as well as between MEH and GREAT, was equal to a half of a spin, making non-MISS judgements significantly harder to achieve.
• Spinners being too short may have prevented them from being fully cleared.
• All spinners required half of a spin more to complete.

Replays set prior to May 10, 2019 (when the change was introduced in the Cutting Edge version) use this old algorithm rather than the one currently in effect.

Notes