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Mortgage repayment calculator

Your real repayments, with interest calculated daily the way lenders charge it. Test rate rises, offsets and extra repayments.

over at , paying , with and . .

Tap any underlined value to change it.

Repayment, monthly $0/mo
Total interest $0
Loan paid off –
vs your term –
Your balance, over the loan

Change anything and the ball rolls down your balance curve to the new payoff date. Hover the curve to read your balance at any point. Drag a rate-change node on the chart, or tap its pill below the chart to type an exact rate and slide when it starts.

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At a glance

Repayments at nearby sizes and rates.

Monthly principal-and-interest repayments over your 30-year term, from the same daily-accrual engine as the calculator above. The highlighted column is your current rate.

Loan amount 5.50% p.a. 6.00% p.a. · yours 6.50% p.a.
$500,000$2,840/m$2,999/m$3,162/m
$600,000$3,409/m$3,599/m$3,795/m
$750,000$4,261/m$4,499/m$4,743/m

Standard principal and interest. Your offset, extras and what-if scenarios are not applied here.

The schedule

Year-by-year breakdown.

Interest, principal and closing balance for every year of your loan, including your offset, extras and any scenarios you have switched on above.

Methodology

How this calculator works

The engine builds your loan day by day. Each day it adds interest of the annual rate divided by 365, applied to your balance net of any offset. Each month it charges the accrued interest to the loan. Repayments land on their actual dates: monthly on your cycle day, fortnightly every 14 days. The minimum repayment is the amount that brings the balance to exactly zero on your final payment, found by simulation rather than formula, because once interest charges monthly against fortnightly payments, no textbook formula is exact.

Most calculators use the standard annuity formula instead:

repayment = P × r(1+r)n / ((1+r)n − 1), where P is the loan amount, r the monthly rate, n the number of months

That formula gives $3,597.30 on the $600,000 example. The daily simulation gives $3,599.35. The $2 monthly gap is the cost of the approximation, and it widens at fortnightly frequency. We show the simulated figure because it matches how your loan contract actually charges.

Scenarios

Testing rate changes and scenarios

Your rate will not stay where it is for 30 years. The what-if cards above turn the scenarios FGO Finance Group works through with clients into one-tap scenarios, and they stack: rates rising while you pay extra with money in offset is one chart, not three. The rate-rise card drops a real rate change onto the timeline, which you can then drag: up or down to change the size of the move, left or right to change when it happens, and you can add more with the button above the chart.

The calculator follows one rule when rates change, because it is the rule lenders follow: your repayment rises when it must and never falls unless you choose. When a rate rises, the lender lifts your repayment to the new minimum and your payoff date holds, so the cost of a rise shows up where you feel it, in dollars per month. When a rate falls and you leave your repayment where it is, every cut goes straight to principal: on the $600,000 example, a fall from 6.00% to 5.00% three years in with the repayment left alone finishes the loan 4 years 11 months early and saves about $212,000 of interest. That number is why keeping your repayments when rates fall is one of the most valuable habits in home lending.

Fixing for a period works the same way: switch the rate type to fixed, choose 1, 2, 3 or 5 years, and set the variable rate you expect to roll to. Your rate becomes the fixed rate, the expiry lands on the chart as a draggable rate change, and the headline shows the repayment step at expiry. On the $600,000 example, 6.00% fixed for 2 years rolling to 6.49% steps the repayment from $3,599 to about $3,787 a month, which is exactly the number to know a few months before your fixed period ends.

Features

Offsets, extra repayments and interest-only

The offset and extra repayment controls model the three features that change a loan's real cost most. The timeline also takes one-off events: lump sums in, redraws out, and ongoing loan fees, each landing on its actual date with interest accruing daily on the result. Add your property value and your own growth assumption and the chart tracks equity and flags when your loan-to-value ratio crosses 80%, a common point where refinancing options open up. An offset account reduces the balance that accrues interest while leaving your minimum repayment unchanged, so the loan finishes early: $255,000 offset against the $600,000 example cuts total interest from $695,767 to about $126,000, and the balance meets the offset around year 11, the point where you could close the loan. Extra repayments work similarly through the principal. Interest-only periods do the opposite: on the same loan, five years interest-only means payments near $3,000 a month during the period, then a step up to $3,868 once it ends, and about $44,700 more interest overall.

FAQ

Frequently asked questions

How are mortgage repayments calculated in Australia?

Lenders calculate interest daily on your outstanding balance (the annual rate divided by 365) and charge it monthly. Your repayment covers that charge first; the remainder reduces principal. Early in the loan most of each payment is interest: roughly $3,000 of the first $3,599 payment on the $600,000 example.

Why does this differ from my bank's calculator?

Bank calculators approximate month by month with the annuity formula. This one simulates daily accrual with monthly charging, which is what loan contracts specify. The difference is about $2 a month on $600,000 at 6.00%, and larger at fortnightly frequency.

Do fortnightly repayments pay the loan off faster?

Yes, when fortnightly means half your monthly repayment, which is what this calculator's fortnightly setting does. That makes 26 half-payments a year, the equivalent of 13 monthly payments instead of 12: on the $600,000 example the loan finishes in about 24.3 years and saves about $156,000 of interest. A lender's recalculated fortnightly minimum, by contrast, spreads the same annual dollars over 26 payments and changes almost nothing.

What happens after an interest-only period?

The balance has not moved, and it now has to amortise over the shorter remaining term, so repayments step up. On the example loan with 5 years interest-only: about $3,000 a month during, $3,868 after.

Does an offset account reduce my minimum repayment?

No. The minimum is set on the loan amount. The offset reduces the interest-accruing balance, so the same repayment clears principal faster and the loan ends years early. Real offset balances move around; because interest is calculated daily, entering your average balance over the loan gives the same interest result as the real up-and-down pattern. An offset also does not change your loan-to-value ratio: lenders assess LVR on the loan balance regardless of offset cash.

What about Lenders Mortgage Insurance?

LMI is a one-off cost some lenders apply to higher-LVR loans, and 80% LVR is a common reference point for it. It is not a fixed rule. Whether it applies, at what LVR, and the premium itself all vary by lender and insurer, and some borrowers, certain professions for example, can borrow above 80% without it. This calculator tracks your LVR as an equity milestone and does not estimate LMI. Ask FGO Finance Group where it applies to your situation.

Why are there no lender rates in this calculator?

You enter your own rate. Showing a specific lender rate inside a calculator triggers comparison-rate obligations under the National Credit Code, and rates most borrowers cannot actually get are misleading. FGO Finance Group can assess what you qualify for across banks, non-banks and private credit.

What happens to my repayments when my fixed rate ends?

Your balance rolls to a variable rate and the lender resets your repayment on the remaining term. On a $600,000 loan at 6.00% fixed for 2 years rolling to 6.49%, repayments step from $3,599 to about $3,787 a month. Set your fixed period and expected revert rate in the calculator to see your own step. Talk to FGO Finance Group two to three months before expiry, because that is when you can refinance instead of accepting the roll-to rate.

What happens to my repayments when interest rates change?

When rates rise, your lender recalculates the minimum and your repayment goes up; you cannot quietly keep paying the old amount, so the payoff date holds and the cost lands in dollars per month. When rates fall, most lenders leave your direct debit where it is unless you ask, and keeping it there is the win: on $600,000 at 6.00% over 30 years, a fall to 5.00% three years in with the repayment unchanged finishes the loan about 4 years 11 months early and saves about $212,000 of interest. This calculator follows that rule: repayments rise when they must and never fall unless you choose.

Related reading

Going further

For an ongoing read on how rates are affecting variable borrowers and what to consider before your next rate review, read the FGO Monthly newsletters. For background on what the 2026-27 federal budget's proposed property tax changes could mean for investors and borrowers, the Off the Desk budget reaction covers the negative gearing, CGT, and serviceability implications, noting these reforms are not yet law. If you are still working out what you can borrow, the borrowing power calculator gives an honest range with the APRA serviceability buffer applied. Our home loans service covers how FGO Finance Group structures and places residential lending across banks, non-banks and private credit.

Numbers are the start. Structure is the win.

FGO Finance Group can assess which lender, which structure and which rate you actually qualify for. We compare them across banks, non-banks and private credit, at no cost to you.

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This calculator provides estimates only. Results are based on the information you enter, including the interest rate you choose, and on general assumptions about loan behaviour (interest calculated daily on the outstanding balance and charged monthly). They do not constitute an offer of credit, a credit assessment, a quote, or financial advice. Actual repayments depend on your lender's credit policies, product features, fees and charges. FGO Finance Group Pty Ltd: Jonathan Chan is a Credit Representative (Credit Representative Number 559372) of Finsure Finance and Insurance Pty Ltd, Australian Credit Licence Number 384704.