Amortization Schedule and Calculations

[Kayla C.]

Hello All!

I'm in the process of buying my first piece of real estate, and I'm aware that an amortization schedule/ calculator helps me find out how many years I can shorten my mortgage by making extra payments on the principal. I've been toying around with some online calculators and I've run into an issue so I'm hoping someone can help me out.

Scenario:

Enter Loan Amount, Interest Rate, and Quantity of Payments. (Brings monthly payment to $402.) I am planning on paying an extra $200.00 to the principal each month for 12 months. This shortens my mortgage from 30 years to a little over 15.3 years.

During this first year, I plan on making improvements + investments + other business ventures and I believe I will be able to pay $300 or $400 extra per month on year 2. However, I cannot find a calculator that allows me to enter $200 worth of extra payments for the first 12 months and then $300 worth of extra payments for the next 12 months. Any suggestions, tips, or links would be greatly appreciated!