The name of this convention is Actual/365 Fixed; Also known as

• Act/365 Fixed
• A/365 Fixed
• A/365F
• English

Computation Method:

The number of accrued days is equal to the actual number of days between the start date and the end date.
The year fraction is the number of accrued days divided by 365. Here is the general formula:

\[YearFraction = \frac{Days(StartDate, EndDate)}{365}\]

Where:

The \(Days\) function returns the number of days between two dates.

The days in the numerators are calculated on a Julian day difference basis. In this convention the first day
of the period is included and the last day is excluded.

Warning:

According to ISDA, "Actual/365" (without "Fixed") is an alias for "Actual/Actual (ISDA)" (see ActualActual (ISDA).)
If Actual/365 is not explicitly specified as fixed in an instrument specification, you might want to double-check its meaning.