Finance calculators

Commbank Home Loan Calculator

Updated Aug 24, 2026 By Jehan Wadia
Rate Formulas
Loan Purpose
Your selection controls which home loan products and rates appear in the product list below.
Loan Details
Minimum $10,000.
Between 1 and 30 years.
After this period the loan switches to principal & interest for the remaining term.
Weekly and fortnightly repayments are only available by Direct Debit. They are calculated as the monthly repayment × 12 ÷ 52 and × 12 ÷ 26.
Interest Rate
LVR (Loan-to-Value Ratio) is your loan amount divided by the property value — a lower LVR usually qualifies for a lower rate.
Enter a rate between 0.01% and 20.00% p.a.
Paid on top of your regular repayment, at the frequency selected above.
Use a negative number for a rate cut (−5% to +5%).
New interest rate
New repayment
Change in repayment
Change in total interest

Your estimated repayments

Your estimated monthly repayment
$0.00
Interest rate used
Total interest charged
Total loan repayments
Repayment after interest-only period
Repayment after fixed period
Loan paid off in
Interest saved with extra repayments
Time saved on your loan term
Repayment breakdown
Using a screen reader? Switch to the Year-by-year table view above for the same data in an accessible table.
Year-by-year repayment schedule showing annual repayments, interest paid, principal paid and principal remaining.
Year Rate Annual Repayments Interest Paid (Year) Principal Paid (Year) Principal Remaining

Step-by-Step Solution

Compare with another loan
Scenario A — your loan above
Loan amount
Interest rate
Term / type
Scenario B
Scenario C
Side-by-side comparison of the regular repayment, total interest and total repayments for each loan scenario.
Scenario Loan amount Rate Term Type Regular repayment Total interest Total repayments
Income & Expenses
Before tax, per year.
Enter 0 if you are applying on your own.
Include groceries, utilities, transport, insurance, childcare and entertainment.
Car loans, personal loans and minimum credit card repayments.
Loan Assumptions
A serviceability buffer of 3.00% is added to this rate when assessing capacity.

Your estimated borrowing power

You may be able to borrow up to
$0.00
Estimated repayment
Combined net monthly income
Assessed monthly expenses
Monthly surplus for repayments
Assessment rate (incl. 3.00% buffer)
Total interest over the term
How the rate changes what you can borrow
Estimated borrowing power and repayment at different interest rates, using the same income and expenses.
Interest rate Assessment rate Estimated borrowing power Estimated repayment

Step-by-Step Solution


Introduction

This home loan calculator shows what your repayments could be. Type in your loan amount, your loan term, and your interest rate. You will see your weekly, fortnightly, or monthly repayment right away. You will also see how much interest you pay over the whole loan.

The calculator has two parts. The Repayment Calculator works out what you will pay each week, fortnight, or month — much like our CBA Repayment Calculator. The Borrowing Power tool uses your income and your bills to guess how much you may be able to borrow, similar to a Home Affordability Calculator.

You can also test a few "what if" ideas:

Pick a fixed or variable home loan for an owner occupied home or an investment property, or just type in your own rate. A chart shows how your loan balance drops each year, and a table lists the numbers year by year like a full Mortgage Amortization Calculator. There is also a step-by-step section that shows the maths behind every answer.

These numbers are estimates only. Your real rate and repayment depend on your loan, your deposit, and the lender's checks.

How to use our Home Loan Calculator

Enter your loan amount, loan term, interest rate and how often you want to pay. The home loan calculator shows your repayment, the total interest you will pay, how long the loan takes to pay off, and how much you may be able to borrow.

Repayment Calculator

Loan Purpose: Pick Owner Occupied if you will live in the home, or Investment if you will rent it out. This changes the loan products and rates you can pick. If you are buying to rent, our Investment Property Calculator and Rental Yield Calculator can help too.

Loan Amount: Type how much you want to borrow. This is the price of the home minus your deposit. The lowest amount is $10,000. Work out your deposit first with the Down Payment Calculator.

Loan Term: Type how many years you want to pay the loan back over, from 1 to 30 years. A longer term means smaller repayments but more interest. See the difference with our 30 Year Mortgage Calculator and 15 Year Mortgage Calculator.

Repayment Type: Choose Principal & Interest to pay down the loan, or Interest Only to pay just the interest for a while. If you pick Interest Only, choose how many years that lasts. The Interest Only Calculator shows what happens after that period.

Repayment Frequency: Choose weekly, fortnightly or monthly repayments. Paying weekly or fortnightly can help you pay less interest — see the Biweekly Mortgage Calculator.

Interest Rate: Pick "Choose a product" to use a listed home loan rate, or "Enter my own rate" to type your own rate between 0.01% and 20% p.a. Not sure what rate suits you? Try the interest rate calculator.

Home loan product: Pick a fixed rate or variable rate loan from the list. Fixed loans go back to the variable rate when the fixed term ends. Your LTV Calculator result helps you see which rate tier you fall into.

Extra repayment: Type any extra money you can pay on top of your normal repayment. The calculator shows the interest you save and the time you cut off your loan, just like the Early Mortgage Payoff Calculator.

Interest rate change: Pick a rate rise or rate cut, or choose Custom and type your own change. This shows what your repayment would be if rates move.

Scenario B and C: Type a loan amount, rate, term, repayment type and frequency for two other loans. The table and chart compare them with your loan, in the same way our Mortgage Comparison Calculator does.

Graph or Table: Use the buttons to see your loan as a chart or as a year-by-year table. For a month-by-month view, use the Amortization Calculator.

Borrowing Power Calculator

Gross annual income (applicant 1): Type your pay for one year before tax. Our Gross Annual Income Calculator can help if you are paid hourly.

Gross annual income (applicant 2): Type the yearly pay before tax for the person buying with you. Type 0 if you are buying alone.

Monthly living expenses: Type what you spend each month on food, bills, travel, insurance and fun. A quick pass through the Monthly Budget Calculator makes this number more accurate.

Other loan repayments: Type what you pay each month for car loans, personal loans and credit cards. Check how these affect your DTI Calculator result before you apply.

Number of dependants: Pick how many children or others you support.

Loan term: Type how many years you want the new loan to run for, up to 30 years.

Interest rate: Type the rate you think you will get. We add a 3.00% buffer to check you can still pay if rates rise.

Repayment type and frequency: Choose Principal & Interest or Interest Only, then pick weekly, fortnightly or monthly repayments.

Press Calculate to see your results, or Reset to start again.

Home Loan Repayments and Borrowing Power Explained

A home loan is money a bank lends you to buy a house or unit. You pay it back over many years, plus interest. Interest is the cost of using the bank's money. In Australia, most home loans run for up to 30 years. If you want the plain formula behind any loan, see the Loan Payment Calculator.

What Your Repayment Is Made Of

Each repayment has two parts:

  • Principal – the part that lowers what you owe.
  • Interest – the fee the bank charges on what you still owe.

Early on, most of your payment goes to interest. As your balance drops, more goes to principal. This is why a small extra payment early can save a lot — the Mortgage Interest Calculator shows the split clearly.

Principal & Interest vs Interest Only

Principal and interest (P&I) pays down the loan every month, so you own more of your home over time. Interest only (IO) means you only pay the interest for a set time, often 1 to 5 years. Your payment is smaller at first, but you still owe the full amount when the IO period ends. Then payments jump higher, because you must repay the same debt in fewer years. IO is common with investment loans and with buy to let mortgages.

Fixed Rate vs Variable Rate

A fixed rate stays the same for a set number of years. Your payment does not change, even if rates rise. When the fixed term ends, the loan usually moves to the bank's standard variable rate. A variable rate can go up or down at any time, which changes your payment. If your fixed term is ending, the Refinance Calculator is worth a look.

LVR and Why It Matters

LVR means Loan to Value Ratio. It is your loan amount divided by the property value. If you borrow $600,000 on a $750,000 home, your LVR is 80%. A lower LVR usually gets you a lower rate. An LVR over 80% often means paying Lenders Mortgage Insurance (LMI) — the PMI Calculator shows how this style of insurance adds up. As you pay down the loan your home equity grows and your LVR falls.

Repayment Frequency

You can pay monthly, fortnightly or weekly. Fortnightly and weekly payments are worked out from the monthly amount. Because there are 26 fortnights in a year (not 24), paying fortnightly can chip away at the loan a bit faster. The Mortgage Payoff Calculator puts a date on it.

Comparison Rate

The comparison rate mixes the interest rate with standard fees into one number. It gives a fairer way to compare two loans than the headline rate alone. It works much like an APR Calculator result.

How Borrowing Power Works

Borrowing power is the largest loan a bank thinks you can repay. Lenders look at your income after tax, your living costs, other debts like car loans and credit cards, and how many people you support. Use the Take Home Pay Calculator to check your after-tax pay. What is left over each month is your surplus, and that surplus sets your loan size.

Banks also add a serviceability buffer, usually 3%, on top of the real rate. So a 6% loan is tested at 9%. This checks you could still pay if rates rise. It is why your borrowing power falls when rates go up. Investors are often also checked on a DSCR Calculator basis.

Ways to Pay Less Interest

  • Make extra repayments, even small ones — try the Extra Payment Calculator.
  • Choose a shorter loan term if you can afford the higher payment.
  • Keep your LVR low with a bigger deposit, built up with a Savings Goal Calculator.
  • Compare rates and ask your lender for a better deal.
  • Pay down other debts before you apply, using the Debt Payoff Calculator.

Buying also brings one-off costs. Budget for stamp duty, closing costs and moving costs before you settle. If you are still weighing up your options, the Rent vs Buy Calculator is a good place to start.

These numbers are estimates only. Your real rate, fees and approved loan amount depend on the lender's checks and your full financial situation.


Formulas used

Monthly interest rate from annual rate
i = \frac{r\%}{12 \times 100}
Monthly principal & interest repayment
M = \frac{P \cdot i}{1 - (1 + i)^{-n}}
Interest-only monthly repayment
M_{IO} = P \times i
Repayment converted to chosen frequency (weekly/fortnightly)
R = M \times \frac{12}{f} + \text{Extra}
Monthly amortisation step (interest, principal and balance)
I_m = B_{m-1} \times i, \quad B_m = B_{m-1} - \left( M + E - I_m \right)
Total interest charged over the loan
\text{Total Interest} = \text{Total Repayments} - P
Monthly surplus available for repayments (borrowing power)
S = \frac{G - T}{12} - \max(E, E_{min}) - O
Maximum borrowing power at the buffered assessment rate
L = S \times \frac{1 - (1 + i_a)^{-n}}{i_a}, \quad i_a = \frac{r\% + 3.00\%}{1200}

Frequently asked questions

Does this calculator include fees, stamp duty or LMI?

No. It only works out loan repayments and interest. It does not add:

  • Application or monthly account fees
  • Stamp duty and government charges
  • Lenders Mortgage Insurance (LMI)
  • Council rates, strata and insurance

Add these costs to your own budget before you buy.

What number should I put in the Loan Amount box?

Put in the money you need to borrow, not the price of the home. Take the purchase price and take away your deposit.

Example: a $800,000 home with a $160,000 deposit means you borrow $640,000.

Why does my bank quote a different repayment?

Banks use your real rate, your fee package and their own day-count rules. This tool uses a simple monthly interest method and the rate you picked.

Treat the result as a close guide, not an exact quote.

What does "Repayment after fixed period" mean?

Fixed loans only hold that rate for 1 to 5 years. After that, the loan moves to the standard variable rate.

This row shows the new, usually higher, repayment once the fixed term ends. It is worth checking before you lock in a fixed rate.

Why does the rate change scenario say "after fixed period"?

A fixed rate cannot move while it is fixed. So the calculator keeps your fixed rate for the fixed years, then applies the rise or cut to the variable rate that comes after.

If you chose a variable loan or your own rate, the change applies straight away.

My borrowing power came out as $0. What went wrong?

Your bills and other loan repayments were bigger than your after-tax pay, so there is nothing left over to make home loan repayments.

Try lowering your monthly expenses, paying off a car loan or credit card, or adding a second income.

Why are my assessed expenses higher than the amount I typed?

Lenders use a minimum living cost figure. If your number is lower than that minimum, the calculator uses the minimum instead.

The minimum grows if there are two applicants and if you have dependants. You will see "(minimum applied)" next to the result.

How is the tax in the Borrowing Power tool worked out?

It uses current Australian income tax rates plus the 2% Medicare levy on each income.

It does not include HECS/HELP debt, salary sacrifice, offsets or private health cover, so your real take-home pay may differ.

Does paying weekly or fortnightly show a saving in this calculator?

The weekly and fortnightly figures are the monthly repayment converted to that frequency, so the yearly total stays the same.

To see a real saving, put an amount in the extra repayment box. That is what cuts your interest and your loan term.

Is the extra repayment a one-off or every time?

Every time. It is added to each repayment at the frequency you picked.

So $200 with monthly chosen means $200 every month. With weekly chosen it means $200 every week.

Does the calculator handle an offset account or redraw?

Not directly. But money kept in an offset works much like an extra repayment.

To copy the effect, type an amount in the extra repayment box and see how much interest you save.

My rate is not on the product list. What do I do?

Choose Enter my own rate and type it in. You can use any rate from 0.01% to 20% p.a.

This is handy if you have a discount, a broker quote, or a loan with another lender.

Why are investment loan rates higher than owner occupied rates?

Lenders see investment loans as riskier, so they charge more. Rules from the regulator also push investor rates up.

Switch the Loan Purpose button at the top to compare both rate sets.

Can I use this to compare a refinance?

Yes. Put your current loan in the main calculator, then put the new loan you are offered into Scenario B.

The table shows both repayments and both total interest amounts side by side. Remember to check exit and setup fees too.

Why does interest only cost more in the end?

During the interest only years you pay nothing off the loan. The balance stays the same, so interest keeps building on the full amount.

You then repay the whole loan in fewer years, which means bigger repayments later and more total interest.

What is the longest loan term I can enter?

30 years. That is the usual maximum for Australian home loans.

A shorter term means higher repayments but far less interest. Try 25 years in Scenario B to see the difference.

What does the Step-by-Step Solution show?

It shows the maths behind your answer, one line at a time. This includes the monthly rate, the number of repayments, the repayment formula, and the total interest.

It is useful if you want to check the numbers yourself or learn how loan maths works.

Why do the last rows of the year-by-year table look smaller?

The final year is often a part year. The loan is paid off partway through, so the totals for that year are lower.

If you make extra repayments, the loan ends earlier and the table stops sooner.

Is my information saved?

No. Everything is worked out in your browser. Nothing you type is sent or stored.

Refreshing the page clears your numbers, so write down or screenshot any results you want to keep.

Can I use this calculator if I am buying with someone else?

Yes. In the Borrowing Power tab, put one income in each applicant box.

The tool taxes each income on its own, then adds them. It also uses a higher minimum living cost for two people.