Overall difficulty
For recommended OD values, see: Ranking criteria
Overall difficulty (OD) defines how difficult it is to achieve high accuracy on a beatmap. The value ranges from 0 to 10, where higher OD will require more accuracy and precision. Since accuracy is important for gaining health, overall difficulty also influences how hard it is to pass a beatmap.
Timing
Higher OD values mean shorter time windows to clear hit objects, both in general and in terms of getting high score values. The maximum allowed hit error for each hit object in osu! and osu!mania, centred on the hit object's correct time, is defined by the tables below.
Note that in the stable version of osu!, hit windows in osu! and osu!taiko can effectively be up to 0.5 ms shorter on both sides than what the formulas suggest, and in osu!mania they can be up to 0.5 ms longer on both sides. This is because in osu! and osu!taiko, a hit is considered inside a hit window if hit error < round(hit window), while in osu!mania it is considered inside if hit error <= round(hit window).1
For example, the hit window of a Great in osu!taiko at OD 5 is ±34.5 ms, instead of the ±35 ms the table gives. In osu!mania, the hit window of a MAX is ±16.5 ms, not ±16 ms as the table suggests.
Hit windows for judgments can be viewed when hovering over the beatmap information in song select, which will always show the correct values.
osu!
| Score | Hit window (ms) |
|---|---|
| 300 | 80 - 6 × OD |
| 100 | 140 - 8 × OD |
| 50 | 200 - 10 × OD |
Comparison of hit windows for different combinations of OD and game modifiers. For Half Time and Double Time combinations, the shown OD values are only valid for the hit windows of 300s, and would be different for 100s and 50s.
osu!taiko
| Score | Hit window (ms) |
|---|---|
| Great | 50 - 3 × OD |
| Ok | 120 - 8 × OD if OD ≤ 5, and 110 - 6 × OD if OD ≥ 5 |
| Miss | 135 - 8 × OD if OD ≤ 5, and 120 - 5 × OD if OD ≥ 5 |
osu!mania
| Score | Hit window (ms) |
|---|---|
| MAX | 16 |
| 300 | 64 - 3 × OD |
| 200 | 97 - 3 × OD |
| 100 | 127 - 3 × OD |
| 50 | 151 - 3 × OD |
If the player hits outside of the 50's hit window, it will count as a miss. In case the hit windows of two objects overlap, the second object will be inaccessible until the first object disappears due to notelock.
Sliders and spinners
In osu!, sliders will reward a 300 as long as they are hit within the 50's hit window. This is sometimes called slider leniency and is removed in ScoreV2.
Overall difficulty also affects spinners, in that they must be spun more to fill up the gauge in time. In osu!taiko, the denden will also need more hits to be cleared. The spins per second required to clear a spinner is defined by the following formula:
- OD < 5:
5 - 2 × (5 - OD) / 5 - OD = 5:
5 - OD > 5:
5 + 2.5 × (OD - 5) / 5
Mod effects
There are four mods that alter the overall difficulty when activated:
- Easy: Halves the OD value.
- Hard Rock: Multiplies the OD value by 1.4, up to a maximum of 10.
- Double Time: The OD value is not affected, but due to the 50% play speed increase, hit windows are 33% shorter.
- Half Time: The OD value is not affected, but due to the 25% play speed decrease, hit windows are 33% larger.
While Half Time and Double Time do not change the OD value, the speed difference leads to a change in the hit windows. Because the scaling is different for each score value, DT causes the windows for 100 and 50 to become tighter than usual compared to 300, and HT causes them to become more lenient.
osu!catch
Overall difficulty is visible when viewing beatmap information, but it does not affect gameplay.