Loan amortization calculation depends on the three simple factors; namely principal, rate and time period. One can put the variants correctly and deduce the interest he has to pay yearly and therefore monthly.

Higher principals generally are loaned at lower interests and lower principals at higher rates. Time factor is a great deciding factor and longer period payoffs entail lesser interest per month naturally. But that is a mirage as it is hard to foreclose longer period loans.

Additional payments of even small quantity might save much interest over the period for the borrower. This additional payment of course cuts down on the principal and one can divide straight as to how less time he would require paying the full loan. Thus, one just needs to do simple calculation to find out his monthly payments. Interests are compounded on the principal as the years go by however. One needs to heed to that.