Interest and Amortization Mortgage Calculator

The boring, but necessary, stuff: This calculator is provided to you without express or implied warranty and is to be used as an informative guide only. Please verify all payment information with your lender directly. You are free to redistribute this calculator, but you must leave it as is, with the attribution in place. If you are a website owner, and wish to provide this for free to your clients or web site visitors, we can provide you with a co-branded version (with your logo and contact information). Please contact us through one of our social media accounts above. If you have any other comments, questions or suggested improvements, please contact through the same methods, as well. We would love to hear from you!

General Information: This spreadsheet works the same as any other mortgage loan calculator / amortization spreadsheet, with the addition of a few notable features:

  1. You can determine how much in interest costs you will save, and as a result, how much sooner your mortgage (or other loan) will be paid off if you pay over the amount of your scheduled payment in any given month.
  2. It provides up-to-date payoff amounts for each month that you will be making payments.
  3. It provides monthly interest cost and principal reduction figures, so that you can see how much of a dent you are making in your mortgage balance in a given month.

This calculator is “live”, meaning, that any time that you change one of the inputs, the spreadsheet recalculates automatically. If you do not want to see this screen first next time, simply re-save this file when you are on the calculation screen. The next time you open this file, the calculation screen will be the default. Also, if you do not see any individual payment information, simply scroll up within the spreadsheet. The displayed length adjusts automatically according to how many payments will be required to pay off your loan. It does not automatically reposition the pointer within the spreadsheet, and that is because the extra rows do not truly disappear. They are simply masked from view. We did it this way, because coding the spreadsheet, without using macros, would allow it to operate on a friendly basis with security programs.

This calculator is designed to get you to focus on how you can save money on your interest costs, so please keep the following in mind:

  1. This is a simple interest calculator will work with any fixed rate and term (1-30 years) loans. Use it for car and personal loans, also. This calculator, however, does not account for adjustable interest rates. A future version will have this capability.
  2. This calculator works off of your total loan balance, not the amount that you actually receive. Enter your interest rate, not your APR.
  3. While most mortgage calculators allow input for taxes and insurance, this one does not. These amounts are subject to change over the course of a loan and could provide misleading results. Add these figures manually.
  4. This calculator does not consider the possibility of late payment or other fees being added on during the course of your loan.

This calculator is “live”, meaning, that any time that you change one of the inputs, the spreadsheet recalculates automatically. If you do not want to see this screen first next time, simply re-save this file when you are on the calculation screen. The next time you open this file, the calculation screen will be the default. Also, if you do not see any individual payment information, simply scroll up within the spreadsheet. The displayed length adjusts automatically according to how many payments will be required to pay off your loan. It does not automatically reposition the pointer within the spreadsheet, and that is because the extra rows do not truly disappear. They are simply masked from view. We did it this way, because coding the spreadsheet, without using macros, would allow it to operate on a friendly basis with security programs.

This calculator is currently available in Microsoft Excel and Google Spreadsheet (Docs) formats.

Download the Microsoft Excel version

Google Spreadsheet (notes): There are two locations that you can obtain the Google Spreadsheet version from. It is currently available in Google Template Gallery (titled: “Mortgage Interest Savings Calculator” or simply via a link. If you use the direct link, keep in mind that this version is read only. You need to save a copy of the file to your account so that you may edit it.

Get a Copy Direct Share from Google Docs or Google’s Template Gallery

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