A previous poster explained what I also need; there were no responses,
so I thought I would try again.

Does anyone know of an Excel template--or a small stand-alone
program--that will calculate the interest/principal breakdown when
payments are varied in amount and frequency? Free or low-cost, please.
I need one that will work on my Mac/Office 2004. I will need to print
out periodic reports.

Here is the way the previous poster described it:
"Excel template: Loan Amortization for random/irregular payments,
figures days
between payment dates.
I have a loan with a variable beginning balance and irregular payments
with
annual large payment. (based on collections)
Would like to enter payment and date.
then Excel would figure days since last payment, interest amount,
principal
amount, Ending Principal balance.
And total interest paid, total pricipal paid
If I change the starting principal, excel would recalculate all
entries."

Thanks very much.

Microsoft offers this template

http://office.microsoft.com/en-us/te...xIn stalled=1

....which you could alter to do the things you need.