General
All of these day count conventions are calculated by taking as the numerator the actual number of days between the start and end of the period. The denominator is 360, 365 or 366 depending on the actual convention used.

Actual/360
The number of days in the period divided by 360.

Actual/365 Fixed
The number of days in the period divided by 365.

Actual/366
The number of days in the period divided by 366.

Actual/252 differs significantly from all other day count conventions in that its numerator is calculated as the number of business days between two dates and the denominator is 252, which is the average number of business days in a year in Brazil.

In order to calculate the day count fraction you must know the calendar of holidays between the start and end date of the period in order to be able to count the number of valid business days; the number of days which are not weekends or national holidays.

Once you have the count of business days the calculation is simply:

Number of busines

General

All 30/360 day count conventions are based upon the numerator being calculated according to a consistent month length of 30 days and a denominator based upon a year being 360 days.