Mortgage Payoff Calculator
Use your own numbers after reviewing the example below.
Quick answer
An extra $100 each month reduces principal faster, which usually shortens the payoff period and lowers future interest on a standard fixed-rate amortizing mortgage.
Formula or method
Step-by-step
- Enter the current balance, rate and years remaining.
- Calculate the scheduled principal-and-interest payment.
- Add $100 each month and simulate the declining balance.
- Compare payoff months and total interest.
Worked example
On a $200,000 balance at 5.5% with 20 years remaining, the scheduled principal-and-interest payment is about $1,375.77. In the site calculator, adding $100 monthly produces an estimated payoff earlier than the original 240-month schedule.
How to interpret the result
The benefit is larger when there is more time remaining and the interest rate is higher, but the exact result depends on your loan terms and payment timing.
Common mistakes
- Sending extra money without confirming it is applied to principal.
- Including escrow in the principal-and-interest calculation.
- Ignoring prepayment terms or other higher-priority cash needs.
Frequently asked questions
Will $100 extra always save interest?
On a standard amortizing loan where the extra is applied to principal, reducing the balance sooner generally reduces future interest.
Does the monthly required payment change?
Usually not on a standard fixed-rate mortgage unless the loan is recast or modified.
Should I mark the payment principal only?
Follow your lender’s instructions for extra principal payments.