Need help with calculating a formula, please!

I’m reading through the book “Weekend Millionaire’s Secrets to Investing in Real Estate”, and have been plugging some of the formulas (such as NOI, and ROI) into a spreadsheet, so I can show my reluctant DH some numbers (and give him reasons why we NEED to get started in REI), and also just get myself familiar with some of the calculations that are used in REI, so I have a better handle on the math of it.

A calculation that has me stumped is the chart on page 151 in the book, titled “Amounts you can pay off with a $750 mortgage”. In the example given, if you know that the asking price of a property is 90K, you can see, using the chart, that you can pay this price for 15 yrs at 5-6%, over 20 yrs at 7-8%, or over 25 yrs at 8-9%.

So with the formula that I am looking for, I can enter the desired mortgage pmt., the interest rate, and the length of the loan, and the result should be the amount to be mortgaged.

I really am not great at math, so I hope that I’m explaining the formula that I’m looking for well. If you know what I’m talking about, you can either tell me the formula in a way that would work in Excel, or just spell it out for me for use with a calculator.

Hope you can help, and thanks in advance for trying!

If you are REALLY serious about real estate investing, I recommend that you go out and spend the $30 to buy a buisness calculator…I use mine (a Hewlitt-Packard 10BII) just about every day. It will perform these sorts of calculations and a whole lot more…plus, it’s portable!


This will tell you how much your payments will be:

And this calculator will show you the benefits of making extra payments:

Or in excel, click File - New. Then from the Templates, choose Loan Amortization.

I do not know the formulas, but if you search Google or something using the term amortization, you should be able to find it.