Mortgage Repayments Calculator

Open Investment Tools → Mortgage & Borrowing, then choose Mortgage Repayments.

What it helps you answer

Use this calculator to compare principal-and-interest repayments with interest-only repayments at
weekly, fortnightly, or monthly frequencies.

Enter the loan amount and term, select weekly, fortnightly, or monthly repayments, then choose an
available advertised interest rate or enter your own.

How the calculation works

Principal-and-interest repayments use the standard amortised-loan formula at the selected repayment
frequency. The interest-only comparison is the loan amount multiplied by the annual rate and divided by
the number of payments per year. Total repaid and total interest use that same selected frequency, so
the headline repayment and totals reconcile.

The projection assumes the selected interest rate applies for the full loan term. It does not model
refixing, fees, council rates, insurance, or lender-specific repayment rules.

What the results show

Review:

• the principal-and-interest repayment at the selected frequency
• the interest-only repayment for comparison
• total repaid and total interest across the term
• a chart of the remaining balance, cumulative principal, and cumulative interest over time

What to look for

An interest-only repayment may be lower now but does not reduce the principal. The interest-only figure
is a comparison, while the displayed term totals are based on principal-and-interest repayments.

Advertised rates can change and may not be the rate a lender offers you. Results exclude lender-specific
fees and eligibility rules. See Mortgage Rates and
Contacting an adviser.