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Mortgage Calculator with Extra Payments calculate mortgage interest savings


How fast will I pay off a mortgage?

How fast you'll pay off a mortgage if you make extra payments depends on several factors, chief among them are:

  • the mortgage loan amount
  • the mortgage interest rate
  • the amount of the extra payment; and
  • the original term (number of payments)

The below mortgage calculator with support for extra payments will quickly calculate the answer for your circumstances, but here's an example.



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An Example:

According to the Mortgage Bankers Association, the average size of new 30-year mortgages in the U.S. is approaching $400,000, and interest rates are hovering around 3%.

To calculate how long it will take for the mortgage holder to pay off the average mortgage, set up the calculator this way:

  1. Mortgage Amount (or current balance): 400,000.00
  2. Number of Payments: 360 (original 30-year term)
  3. Interest Rate (Annual): 3.0%
  4. Mortgage Payment Amount: $1,682.42
  5. Pay this Extra Amount: $200.00
  6. Extra Payments Start: <as appropriate>
  7. Number of Extra Payments: Unknown
mortgage calculator with extra payments
Pay off your $400,000, 30-year mortgage in a little over 25 years and save over $36,000 in mortgage interest by making $200 additional payments.

Assuming the above scenario, you'll pay off your $400,000 in a little over 25 years, and perhaps the best part, you'll save over $36,000 in mortgage interest charges.

The Mortgage Payment Schedule with Extra Payments


The calculator supports schedules with:

  • a specific number of additional payments; or
  • extra payments until you've paid off the loan; or
  • extra payments at a different frequency than the "regular payment" - try making two extra payments a year; or
  • additional payments on dates other than a scheduled date; or
  • a single lump-sum extra payment on any date
Mortgage schedule showing extra payments
Mortgage schedule showing extra payments.

Also, take a moment to study the mortgage payment schedule. Observe the lines where you've paid an extra amount. Notice that 100% of the amount gets applied to the principal balance. But if you are auditing your lender, they must apply the payments in the same way if you want to maximize your interest savings. Some lenders may not do this, particularly if you make the extra payment on a date other than a scheduled due date.

Interestingly, a lot of online calculators are not capable of making the correct calculation either. That's why this calculator is the real deal!

Important usage notes about this calculator:

  • The calculator will calculate the regular periodic payment for you if you enter a "0". If you know the amount, you can enter it, and the mortgage schedule will use it.
  • If you want to calculate the interest, you'll save on an existing loan start by entering the loan's current balance and the number of remaining payments.
  • Assume you've received a large bonus, and you want to calculate the result of making one lump-sum payment. To do so, change "Unknown" to "1" in step 7.
  • Always enter (and reenter) a 0 if you want a value calculated. Why doesn't the calculator automatically recalculate the last unknown? We want the calculator to create an amortization schedule using whatever parameters you want to use. This is a feature! By not automatically recalculating the payment (for example) when the mortgage amount changes, this calculator lets those users create a payment schedule with whatever payment amount they want.

Comments, suggestions & questions welcomed...

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