Mortgage extra repayment calculator

What the result means

Extra principal each month shortens the term because less interest accrues later. The scheduled repayment stays the same; you choose to pay more.

How it is calculated

Each month: interest = balance × r/12; extra reduces principal after interest is charged

• Extra: Additional monthly principal.
• r: Nominal annual rate.

The loan is simulated period by period. Interest saved is the difference versus making only the scheduled repayment.

Worked example

$400 extra on a $680,000 loan at 5.8%

A 30-year monthly loan with an extra $400 every month.

Scheduled repayment

About $3,990

Paid

About $4,390

Effect

Term and total interest both fall

The headline saving is interest not paid, not extra cash in your pocket today.

Check redraw, offset and lender rules

Some loans allow extra repayments and redraw; fixed-rate products may cap extra amounts. An offset account can be a better fit if you need the cash later — compare with the offset calculator.

This model assumes the extra amount is paid every month until the loan ends, with a constant rate and no fees.

Questions