Click on the picture below for an easy to use Loan Amortization Calculator.
This will take you to an excellent site for mortgage calculating,
I have it set to their simplest calculator but if you are an expert
you may want to check out some of their more complicated ones.
ALWAYS ask your lender for a "Truth in Lending Statement"! A lower interest rate doesn't always mean the best deal, they may have hidden/junk fees that raise your payment above that of another higher interest rate.