Simple interest question

[Captain825]

Ok, I've thought myself into a frenzy over this simple interest calculation and I would appreciate some input.

The sheet calculates simple interest on monthly charges.

C13 E18
18% INTEREST # of days

C18 D18 F18 G18 H18
From To Principal Principal Total Calculated Interest
1/1 1/31 $250.00 $250.00 $3.82
2/1 2/28 $250.00 $500.00 $6.90

Here is my formula
=IF(C18="","",IF(D18="","",IF(F18="","",(G18*$C$13)/365*E18)))

I feel that to capture the total interest due, the "To" date should be today's date and not just the end of the month as in the example below.

C18 D18 F18 G18 H18
From To Principal Principal Total Calculated Interest
1/1 5/6 $250.00 $250.00 $15.53
2/1 5/6 $250.00 $500.00 $23.42

Am I not correct?

Thanks
Adrian

 

[Scott R]

If you added simple interest on $250 for Jan, Feb, Mar, Apr, and 6 days of May, you get $3.82+$3.45+$3.82+$3.70+$0.74, or $15.53. So not sure what your problem is exactly. Without compounding, they both look right.