How Can You Calculate Interest Rates?

"The" interest rate, being that which the Fed charges to banks and institutions, is not so much calculated as devised. It is a number that exists because it has existed. The Treasury department makes adjustments to the number upwards or downwards as they see fit. After that there is what is called the "Prime" rate, which may typically be a half point above the Fed rate, and which is agreed upon by the Federal Reserve System members for favored lending rates on a week to week basis. A "Commercial Rate" would be that rate decided upon by a bank for its favored lenders based on some what point system they choose above the "Prime" rate. The "Consumer Rate" is their adaptation of that according to the banks' own individual criteria based on their business conditions and projections in conformance with a matrix they create for varying credit risks. There is no hard and fast computation of interest rates at this level. But when amortizing for a loan, calculating the amount that goes into the portion of interest, is a mathematical formula usually based on a division of the interest rate by 360 days on the existing balance.

I think the best thing to do is check out the sites listed below for calculators that can help --

GOtalkmoneym
DinkyTownt