Extra Mortgage Payment Calculator
See how extra monthly principal cuts your payoff time and total interest.
Inputs
Result
Visual breakdown
Formula
Each month, interest = balance × APR/12 accrues, then payment reduces the balance. Adding extra principal shrinks the balance faster — saving future interest and shortening the term.
Example
$300k @ 7% with $2,000 base + $300 extra → years off the loan and tens of thousands less interest.
Related: Mortgage · Amortization · Refinance
How to use
- Enter your current loan balance and rate.
- Enter remaining months and your current monthly payment.
- Try different extra amounts to see the impact.
When it's useful
- Deciding whether to round payments up.
- Comparing extra principal vs investing the difference.
- Planning a payoff date before retirement.
Common examples
Frequently asked
Does this assume the extra applies to principal?
Yes — confirm with your lender that extra payments are credited to principal, not pre-paid interest.
Is there a prepayment penalty?
Most US mortgages don't have one, but read your loan terms first.
Better to refinance or pay extra?
It depends on the new rate and closing costs. Use the Refinance Break-Even calculator alongside this one.
Does it model escrow?
No — taxes and insurance aren't included. Use principal & interest only here.
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More money & work →Estimates only — not financial advice.