# Is there a difference between a 360/360 day count convention and a 30/360?

Are these just different names for the same thing? Lending Management Software company told me their software does not do 30/360, but could do 360/360 which would be the closest match. I am thinking it is just an uncommon naming convention, and they are the same thing.

Here is what the software (lending management software) told me: Here is an excerpt from our User Guide: “the per diem interest is the annual interest divided by the number of payments in a year, divided by the number of days in the current payment period. This interest year is inherent in the amortizing equations. For each interest year, you may calculate the APY by multiplying the APR by the factor listed in the table below (not accounting for fees and charges)."

and

"360/360 - (Prin x Int)/(# of annual payments x # of days in current payment period)"

• Where are you seeing 360/360? The only reference I can find online shows that they are the same. May 5, 2018 at 14:13
• Software company told me their software does not do 30/360, but could do 360/360 which would be the closest match. I am thinking it is just an uncommon naming convention, and they are the same thing. This paper for example seems to indicate they are two names for the same thing: business.nasdaq.com/media/day-count-fractions_tcm5044-53854.pdf But like you say, it is hard to find any info on 360/360. Wikipedia only has 30/360. May 6, 2018 at 18:53
• Based on what I have found they are the same thing, however to be certain you could ask the company for their definition of 360/360 and see if it matches the 30/360 convention. May 7, 2018 at 13:33
• thanks D Stanley for following up. Here is what the software (lending management software) told me: Here is an excerpt from our User Guide: “the per diem interest is the annual interest divided by the number of payments in a year, divided by the number of days in the current payment period. This interest year is inherent in the amortizing equations. For each interest year, you may calculate the APY by multiplying the APR by the factor listed in the table below (not accounting for fees and charges)." and "360/360 - (Prin x Int)/(# of annual payments x # of days in current payment period)" May 7, 2018 at 23:44
• This is quite clear, and I can answer if it is taken off hold. Lack of understanding of the topic should not mean that a topic is closed because it is "unclear." May 9, 2018 at 11:49