Sometimes I just need a quick calculator, and I can't find it on my computer. So, I'll just use this one.
Personal Interest Calculator
It's all in JavaScript!
This is a pretty easy calculator, first enter the number of payments you will be making. 30 years = 360 months, for 20 years = 240 months, 15 years = 180 months. Next use the prevailing interest rate and the principle is the amount you would be financing. Click on the compute button for your answer.