If you have a loan or mortgage, probably you have ever think about paying more money on top of your monthly payment to lower the amount of the total interest paid, as well as shorten the payment period over the life of the loan. And usually you think about this after you gain some profit in your investment, your salary is raised, or probably you won some lotteries …:-).
In loan terms, it is called extra payment. Instead of thinking about making additional payment, you can use this calculator to calculate the impact of your extra payment to your existing loan or mortgage. You can also plan to make extra payment regularly whether paying it monthly, quarterly, semi-annually or annually.
The result will give you a rough calculation about how much your interest can be saved on how long your loan period can be shortened. I state this calculation is rough because usually there are additional calculation or penalties applied to your extra payments based on your initial loan aggreement.
This spreadsheet consist of two worksheets, where in the first worksheet you can put your extra payment plan in term of amount and payment period, and you can see the result of your loan without and with extra payments.
In the second worksheet, there is the extra payment amortization table where you can see the profile of your loan with extra payment every month. You can see also in the table or in the picture above that the extra payment amount goes toward the principal, which lowers the total dollar amount that can be charged interest.
Feel free to play around with your numbers and you can download the file here.