See also: osu! judgement system
The score given by each hit circle and end of a slider is calculated with the following formula:-
Score = Hit Value + (Hit Value * ((Combo multiplier * Difficulty multiplier * Mod multiplier) / 25))
|Hit Value||The hit circle judgement (50, 100 or 300), any slider ticks and spinner's bonus|
|Combo multiplier||(Combo before this hit - 1) or 0; whichever is higher|
|Difficulty multiplier||The difficulty setting for the beatmap (see next header)|
|Mod multiplier||The multiplier of the selected mods|
Additionally each slider start, end and repeat tick awards 30 points, each slider middle tick awards 10 points and each spin of a spinner awards 100 points.
Additional bonus of 1,000 points given for each spin of a spinner after the spinner meter is full.
The Difficulty multiplier equals the old star rating. It can be calculated via the following formula:
Stars = Round((HP Drain + Circle Size + Overall Difficulty + Clamp(Hit object count / Drain time in seconds * 8, 0, 16)) / 38 * 5)
Note that game modifiers (like Hard Rock/Easy) will not change the Difficulty multiplier.
It will only account for original values only.