30 360

Subtype of Name

US convention
Also known as 30/360 or 360/360
Let [T₁,T₂) be the period between two dates T₁ and T₂, of which the length L in annual units must be calculated
Calculation rule:
Let N be the effective number of days of the period [T₁,T₂), formally defined as the difference: T'₂ - T'₁, with the effective starting date T'₁ and ending date T'₂ differing from T₁ and T₂ in the following occations:
If T₁ is the 31ˢᵗ of a month or the last day of February, then T'₁ becomes equal to the 30ᵗʰ of the same month.
If T₂ is the 31ˢᵗ of a month and T₁ is the 30ᵗʰ or 31ˢᵗ of a month, then T'₂ becomes equal to the 30ᵗʰ.
If T₂ is the last of February and T₁ is also the last of February, then T'₂ is set to 30.
Then
L = N/360