The easy way to determine principal is to deduct the ending balance from the
beginning balance. Interest, then, would the the total of all your payments
less the principal calculated in the first step.

If you want to break it down into year by year values, you'll again need to
know the starting principal balance, but you'll also need to know the
periodic interest rate and how interest is calculated (in other words, is it
calculated an an actual day basis, on a 30/360 basis (most fixed rate home
mortgage loans are this way), or an actual/360 basis.

"Lisa" wrote:

I'm trying to get a come up with an easy way to figure out how much I paid on
principal and interest on a loan. The only problem is that the payments vary
from year to year. Does anyone have any ideas??