The Home Mortgage Calculator by Vertex42.com is much more than just a run-of-the-mill online mortgage calculator. It is a template for Microsoft Excel that gives you the flexibility of a spreadsheet in addition to providing a fairly comprehensive set of automated features and options. Analyze both fixed-rate and variable-rate loans and mortgages. View and print the amortization schedule. Compare monthly payments to biweekly payments. Analyze a new loan or set up the spreadsheet to analyze your existing mortgages. Run what-if scenarios and save each scenario by simply saving a copy of the spreadsheet. Calculate how much interest you can save by making scheduled or lump-sum extra payments. See how your tax deduction changes over time. Check what your balance will be at a specific year in the future. --- There is extensive help information embedded in the various cell comments. The spreadsheet is not password protected, so if you are an adventurous sort, you can see all the formulas used. The main type of mortgage that this spreadsheet is NOT designed for is a "simple interest mortgage" where the interest accrues daily (but you can find a spreadsheet for that on Vertex42.com as well).