Recurring extra principal
The same additional amount is modeled with every monthly payment until the balance reaches zero.
Extra Mortgage Payment Calculator
Calculate how recurring extra principal payments can reduce mortgage interest and shorten your payoff time.
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Estimate details
⌁ All calculations run locally in your browser. No data is stored.
Interest saved$135,115
Time saved9 yr 2 mo
New payoff time20 yr 10 mo
New monthly payment$2,196
Extra payments are applied directly to principal after the scheduled payment each month.
Pay down principal faster
How additional mortgage payments affect your loan
Mortgage interest is charged against the outstanding principal. When an additional payment is applied directly to principal, later interest charges are calculated on a smaller balance and more of the scheduled payment can reduce principal.
Earlier payoff
The required payment is held constant, so the lower balance normally shortens the number of payments rather than reducing the next bill.
Interest comparison
The original and accelerated schedules are compared to estimate total interest saved over the remaining loan.
Extra monthly payment vs. lump sum
Use this calculator for a recurring additional principal payment. If you plan to use a bonus, inheritance, or other one-time amount, the Lump Sum Mortgage Payment Calculator models that payment directly.
A true biweekly schedule creates 26 half-payments per year. Compare that approach with the Biweekly Mortgage Payment Calculator.
How to use the estimate responsibly
- Enter the current principal balance, not the original loan amount.
- Use the note rate from your loan statement.
- Enter the actual remaining term.
- Confirm how your servicer labels and posts principal-only payments.
The calculation excludes taxes, insurance, escrow changes, investment returns, servicing fees, and possible prepayment penalties.
This is a fixed-rate amortization estimate. Confirm payment-posting instructions and prepayment terms with your mortgage servicer before changing your payment strategy.
How this calculator works
The calculator amortizes the remaining fixed-rate balance twice: once with the scheduled payment and again with the entered additional principal applied every month. Comparing the schedules produces the estimated interest and time saved.
Change any input to update the estimate instantly. Your entries never leave your device.
Read how SimpleCalc defines formulas, assumptions, and accuracy checks.
Frequently asked questions
Does an extra mortgage payment reduce next month’s required payment?
Usually no. It reduces principal and shortens the payoff time while the scheduled payment remains unchanged unless the lender recasts the loan.
Is an extra payment applied to principal automatically?
Not always. Follow your servicer’s instructions and verify that the additional amount is posted as a principal-only payment.
Are prepayment penalties included?
No. Check your loan agreement or ask your servicer before making additional payments.
What is the difference between extra principal and a lump-sum payment?
Extra principal is modeled as a recurring monthly amount. A lump sum is a one-time payment that reduces the balance at a specific point.
Can I use this for one additional mortgage payment per year?
Convert the annual amount to a monthly equivalent for a rough comparison, or use the Lump Sum Mortgage Payment Calculator to model a one-time payment directly.