The difference here is that this calculator is run completely on the client machine using JavaScript, and the source code is available for you to inspect: just click on View|Source.
Enter values for Principal, Interest, Years, Points, Fees, and Precision. (Generally, you should leave Precision = 0.0001 unless you have a special reason for changing it.) Then click the "Calculate" button and the calculated values for Proceeds, Payment, and APR will be displayed.
Disclaimer: BDS Software does not warrant or guarantee this Mortgage Calculator's results. It is a demonstration of our capabilities only. Although it may be used as a helpful guide for your loan transactions, you should consult your own financial institution for exact figures.