The Interest IQ interactive mortgage laboratory

There's more to your mortgage than the interest rate.

Go beyond the ordinary repayment calculator. Explore daily interest, repayment frequencies, offsets, extra payments and rate changes—with an Australian-style day-by-day loan simulation.
Advanced calculator preview · No login required during testing · Calculations are estimates
INTERACTIVE MORTGAGE EXPLORER

Explore the numbers. Understand the difference.

Start with an extra $1 a day or build a more detailed loan scenario with transactions, repayment changes and an offset account.

Start with a small extra repayment. Select a daily amount below to add a recurring extra transaction to your loan, then explore what changes. You can edit or remove it at any time. Full controls are available below.

What difference could just $1 a day make?

Add an automated modelled daily extra repayment. In real life, your lender may apply different minimums or processing rules.

Select a daily extra repayment to begin.

Loan

Set start date

Interest rate

Repayments

Set first repayment date
Interest only
Offset accountSupports regular deposits and withdrawals.

Extra transactions

Additional repayments, withdrawals, fees and offset transactions.
Rate changesSee how rate changes could affect the loan.
Monthly repayments
$0.00
Total loan repayments
$0.00
Total interest charged
$0.00
Date paid off
—
Paid in advance / redraw
$0.00

Loan balance

Chart settings
Original loanReduced loanOffset balance

Schedule

Calculation notes

Interest is accrued daily on the interest-bearing loan balance and rounded to five decimal places, then accumulated and charged monthly after rounding to cents. Monthly dates preserve the original day where possible and use the last day of shorter months. Rate changes are treated as announcements and take effect after the current monthly interest period. Results are estimates; lender policies can vary.