FREE MORTGAGE CALCULATOR · AUSTRALIA
See your repayment, interest and path to zero.
Estimate a principal-and-interest home loan in Australian dollars. Switch between monthly, fortnightly and weekly repayments, then model an offset balance and regular extra payments.
- Offset and extra repayments
- Rate-rise scenario
- Figures stay in your browser
MORTGAGE REPAYMENT MODEL
See the repayment—and what changes it.
Use a principal-and-interest loan, then compare an average offset balance and regular extra repayments. Your figures stay in this browser.
Estimated required repaymentA$3,675per month · principal and interest
PrincipalEstimated interest
WITH YOUR OFFSET AND EXTRA24 years 1 month
A$3,875 paid per month
RATE SCENARIOIf the rate were 8.2%
This is a planning scenario, not a lender serviceability assessment.
A$4,487per month
Balance over the loanScrub to inspect any repayment period
After 30 yearsA$0
A$0 with offset and extraA$0 on the standard path
SELECTED PATH
After 1 yearA$588,839A$11,161 principal repaid
After 5 yearsA$536,604A$63,396 principal repaid
After 10 yearsA$450,237A$149,763 principal repaid
HOW TO USE IT
Start with the loan, then test the levers separately.
Use the amount currently owing if you already have a mortgage, or the expected amount borrowed if you are comparing a future principal-and-interest loan. The most useful inputs come from a lender quote or current statement rather than a market average.
- 01Enter the loan amount and rate
Use the actual rate where possible. A small rate difference can become substantial across a long term.
- 02Use the remaining term
For an existing mortgage, enter the years left rather than the original term.
- 03Match the repayment rhythm
Choose monthly, fortnightly or weekly so the displayed repayment fits the lender schedule you are examining.
- 04Add offset and extra amounts carefully
Use a realistic average offset balance and only an extra repayment the household budget can maintain.
THE CALCULATION
How the mortgage repayment model works.
The required repayment uses standard amortisation: the same regular payment gradually covers interest and reduces principal to zero across the term. Each period, the selected path charges interest on the remaining loan balance less the constant average offset, then applies the required and extra repayment.
INTEREST-CHARGED BALANCEremaining loan balance − average offset balance
The result cannot fall below zero. The offset does not reduce the loan principal in the model; the unchanged repayment simply directs more of that period's payment to principal.
Australian lenders commonly calculate interest daily and debit it monthly. This simplified model compounds at the selected repayment frequency, so exact lender dates, daily offset movement, rounding and fees can create differences.
MONTHLY VS FORTNIGHTLY
Frequency and paying extra are not the same thing.
A true fortnightly repayment spreads the amortised annual amount across 26 periods. Some “pay fortnightly” examples instead halve a monthly repayment and pay that amount 26 times. Because 26 halves equal 13 monthly repayments, that method pays one additional monthly amount each year.
VULT calculates the true required repayment for each frequency. If you want to test the accelerated version, put the difference into the extra-repayment field. That keeps the comparison visible instead of hiding the extra payment inside a frequency label.
OFFSET ACCOUNTS
An offset changes the interest base, not the debt itself.
MoneySmart explains that a linked mortgage offset account generally reduces the part of a home loan charged interest. For example, an A$750,000 loan with A$50,000 in offset may be charged interest on A$700,000 while the money remains in the separate transaction account.
Money stays separate
Access, fees and eligibility depend on the account and loan terms.
Principal reduces
Redraw access and extra-payment limits depend on the lender.
Confirm it is linked
An offset only works as intended when the lender has linked it correctly.
RATE-RISE SCENARIO
A comfortable repayment needs breathing room.
The result includes a rate two percentage points above the rate entered because MoneySmart recommends testing a higher rate when considering what may be affordable. It is a household planning scenario, not a borrowing-power result.
As of 22 August 2026, APRA's minimum mortgage serviceability buffer for regulated banks remains three percentage points above the loan product rate. A lender's assessment is broader than this calculator and includes income, expenses, other debts and its lending criteria.
WHEN REPAYMENTS ARE HARD
Get help early rather than trying to optimise a broken number.
MoneySmart says lenders have hardship teams and that earlier contact can leave more options. A hardship variation may temporarily change repayments or loan terms. Free financial counselling is also available through the National Debt Helpline.
COMMON QUESTIONS
Australian mortgage calculator questions, answered plainly.
How are mortgage repayments calculated?
For a principal-and-interest loan, the repayment is the regular amount required to reduce the starting balance to zero across the selected term at the entered rate. The calculator converts the annual rate to the selected monthly, fortnightly or weekly period and uses standard amortisation.
Does paying fortnightly automatically save interest?
This tool calculates a true fortnightly repayment across 26 periods a year. It does not simply halve a monthly repayment. Halving a monthly amount and paying it 26 times creates the equivalent of 13 monthly repayments, so the saving comes from paying more each year. You can model that difference with the extra-payment field.
How does the offset balance work in this calculator?
The entered average offset balance reduces the part of the remaining loan charged interest each period, while the required repayment stays the same. Real offsets are usually assessed from changing daily balances and must be correctly linked to an eligible loan, so lender results can differ.
Is an offset the same as an extra repayment?
No. An offset is a separate transaction account whose balance may reduce mortgage interest while remaining accessible. An extra repayment reduces the loan balance and access may depend on redraw terms. Fees, rates and access rules matter when comparing them.
Does this tell me how much I can borrow?
No. A repayment estimate is not borrowing power or loan approval. Lenders assess income, expenses, other debts, buffers, credit criteria and the property. The rate scenario is for personal planning only and is not a lender assessment.
Does the calculator include stamp duty, LMI or purchase costs?
No. It starts with the loan amount you enter. Deposit requirements, stamp duty, conveyancing, inspections, lenders mortgage insurance, application costs and ongoing ownership costs sit outside this repayment model.
Can I use this for an interest-only loan?
No. This calculator models principal-and-interest repayments from the first period. Interest-only loans keep the principal unchanged during the interest-only period and can have a repayment step-up later, so they need a different calculation.
Useful Australian home-loan sources
Use lender documents for your figures and current public-interest guidance for the wider decision.
FROM REPAYMENT TO HOUSEHOLD PLAN