Finance calculators

CBA Repayment Calculator

Updated Aug 24, 2026 By Jehan Wadia
Rate Formulas

Your loan details

Loan amount and term
Interest rate
Optional. Leave blank to hide it from the results.
Loan purpose
Repayment type
Repayment frequency
Fortnightly and weekly amounts use a periodic rate of your annual rate ÷ 26 or ÷ 52 and repay the loan over the same term.
Interest is charged on your balance less the offset amount each period.
Variable portion: the remainder of your loan amount. After the fixed period ends, the whole loan is modelled at the variable rate.
Your monthly repayments
$0.00
Owner-occupied
Total interest charged
$0
Total loan repayments
$0
Loan end date
Interest saved by offset
$0
Interest saved by lump sum
$0

Principal vs interest

What if interest rates change?

New interest rate
Change in repayment
New repayment amount

Loan balance over time

Repayment affordability indicator

0%28% — comfortable limit35% — stretched limit50%+

Step-by-Step Solution


Introduction

This home loan repayment calculator shows what your mortgage will cost. Type in your loan amount, interest rate, and loan term. You will see your repayment right away — weekly, fortnightly, or monthly.

You can also test different choices. Add extra repayments, an offset account, or a lump sum, and see how much interest you save and how much sooner your loan ends. Pick principal and interest or interest only, and choose an owner-occupied or investment loan. If you have a split loan with a blended rate, you can enter a fixed portion and a variable portion too.

The results include a chart of your loan balance over time, a full year-by-year table, and a "what if rates change" tool that shows how a rate rise or cut would change your repayment. There is also an affordability meter that compares your repayment to your income, plus a step-by-step section that shows the math behind every number.

All amounts are estimates to help you plan. Your real repayment may differ once fees, rate changes, and lender rules are added. For a broader view of a purchase, try our mortgage calculator, home affordability calculator and stamp duty calculator.

How to use our CBA Home Loan Repayment Calculator

Enter your loan amount, term, interest rate and repayment choices. The calculator shows your repayment, total interest, total repayments, your loan end date and a full year-by-year schedule.

Loan amount: Type how much you want to borrow, or drag the slider. This is the price of the home minus your deposit. Not sure how much to put down? Use the down payment calculator.

Loan term: Enter how many years you want to pay the loan off, up to 30 years. A longer term means smaller repayments but more interest. Compare a 30-year loan with a 15-year loan to see the difference.

Annual interest rate: Enter the rate your lender charges each year, like 6.14%. Our mortgage rate calculator can help you test different rates.

Comparison rate: Enter the rate that includes most fees, if you know it. Leave it blank to hide it. The APR calculator works on a similar idea.

Loan purpose: Pick Owner-occupied if you will live in the home, or Investment if you will rent it out. Investors can also check the rental yield calculator and investment property calculator.

Repayment type: Pick Principal & interest to pay down the loan, or Interest only to pay just the interest for a while. See the interest only mortgage calculator for a deeper look.

Interest only period: If you chose Interest only, pick how many years it lasts. The calculator then shows the higher repayment that starts after it ends.

Repayment frequency: Choose Monthly, Fortnightly or Weekly to match your pay cycle. The biweekly mortgage calculator shows the payoff effect of more frequent payments.

Extra repayment: Enter any extra money you can pay each period. The calculator shows the interest you save and how much sooner you finish — the mortgage extra payment calculator and early mortgage payoff calculator explore this further.

Average offset balance: Enter the usual amount you keep in your offset account. This money cuts the interest you are charged.

Lump sum amount: Enter a one-off payment you plan to make, such as a bonus or tax refund. A mortgage recast calculator shows another way lenders handle big one-off payments.

Paid after: Enter how many years from now you will make that lump sum payment.

Split loan switch: Turn this on if part of your loan is fixed and part is variable.

Fixed rate portion: Enter the dollar amount on the fixed rate. The rest is treated as variable.

Fixed rate, fixed period and variable rate: Enter the fixed rate, how many years it is locked in, and the variable rate that applies after.

Interest rate change buttons: Tap a rate move, like +0.50%, to see how much your repayment would go up or down.

Graph view and Table view: Switch between the balance chart and the year-by-year table of principal, interest and closing balance. For a payment-by-payment breakdown, see the mortgage amortization calculator.

Gross monthly income: Pick your income before tax. The meter shows what share of your income the repayment takes. Check your debt-to-income ratio too.

Calculate, Reset and Print summary: Press Calculate to update the results, Reset to start again, or Print summary to save a copy.

Home Loan Repayments Explained

A home loan repayment is the set amount you pay your lender each week, fortnight or month. Every payment is split into two parts: principal (the money you borrowed) and interest (the fee the bank charges you to borrow it). Early on, most of your payment goes to interest. Later, more of it goes to principal, and your balance drops faster. The amortization calculator shows this split in detail.

What Changes Your Repayment Amount

  • Loan amount: A bigger loan means a bigger repayment.
  • Interest rate: Even a 0.25% move can change your payment by a lot over 30 years. Test rates with the loan interest rate calculator.
  • Loan term: A longer term lowers each payment but costs more interest in total.
  • Repayment type: Principal and interest pays the loan off. Interest only does not.

Principal and Interest vs Interest Only

With principal and interest (P&I), your balance shrinks with every payment, so the loan ends on time. With interest only (IO), you pay just the interest for a set period, usually 1 to 5 years. Your payments are smaller, but the balance stays the same. When the IO period ends, payments jump, because you must repay the whole loan in less time. Investors often use IO loans for tax and cash flow reasons — the interest only calculator models this pattern.

Owner-Occupied vs Investment Loans

An owner-occupied loan is for the home you live in. An investment loan is for a property you rent out. Lenders in Australia usually charge a higher rate on investment loans because they see them as riskier. If you are weighing up buying at all, the rent vs buy calculator and rental property calculator are useful next steps.

Repayment Frequency

You can pay monthly, fortnightly or weekly. Splitting your payment into smaller, more frequent chunks can help you match your pay cycle. If you pay half a monthly amount every fortnight, you end up making the equal of 13 monthly payments a year instead of 12, which pays the loan off sooner. Line this up with your biweekly paycheck or weekly pay.

Ways to Pay Less Interest

  • Extra repayments: Any money above your set payment goes straight to the principal, so you pay less interest and finish early. See the extra payment calculator.
  • Offset account: Money in this account is subtracted from your loan balance before interest is worked out. Keep $20,000 in offset on a $450,000 loan and you only pay interest on $430,000.
  • Lump sum: A one-off payment, such as a bonus or tax refund, cuts the balance right away and saves years of interest. The mortgage payoff calculator shows the new end date.

Comparison Rate

The interest rate alone does not show the full cost. A comparison rate rolls the interest rate plus most standard fees into one number, so you can compare loans fairly. Always check both, and put two offers side by side with the loan comparison calculator or the mortgage comparison calculator.

How Much Can You Afford?

A common guide is to keep home loan repayments under 28% of your gross monthly income. Between 28% and 35% is tight. Above 35% is called mortgage stress, and leaves little room if rates rise or your income drops. Because most Australian home loans are variable rate, it is smart to check what your payment would look like if rates went up by 1% or 2%. Work out your take-home figure first with the PAYE calculator or monthly income calculator, then set a plan using the budget calculator.

Split Loans

A split loan puts part of your debt on a fixed rate and part on a variable rate. The fixed part keeps your payment steady for a set number of years. The variable part lets you make extra repayments and use an offset account. It is a middle path between safety and freedom. Also consider your loan-to-value ratio, since it affects the rate you are offered and whether lenders mortgage insurance applies. Later on, a refinance mortgage calculator can tell you if switching is worth it, and the home equity calculator tracks the wealth you build along the way.

These figures are estimates only. Your lender's actual rate, fees and approval terms may differ.


Formulas used

Periodic interest rate
r = \frac{r_{\text{p.a.}}}{p}, \quad p \in \{12, 26, 52\}
Number of repayments
n = \text{Term}_{\text{years}} \times p
Periodic repayment (principal and interest)
M = B \times \frac{r(1+r)^{n}}{(1+r)^{n}-1}
Interest only repayment
\text{IO} = P \times r
Interest charged each period with offset
I_k = \left(\text{Balance}_{k-1} - \text{Offset}\right) \times r
Balance update each period
\text{Balance}_k = \text{Balance}_{k-1} - \left(M + \text{Extra} - I_k\right)
Blended split loan rate
r_{\text{blend}} = \frac{A_{\text{fixed}} \times r_{\text{fixed}} + (P - A_{\text{fixed}}) \times r_{\text{var}}}{P}
Affordability percentage of gross monthly income
\text{Aff}\% = \frac{(M + \text{Extra}) \times \frac{p}{12}}{\text{Income}_{\text{monthly}}} \times 100

Frequently asked questions

Does the calculator work for loans that are not with CBA?

Yes. It works for any home loan from any Australian lender. Just type in your own loan amount, rate and term. The math is the same for every bank.

Why does my fortnightly repayment look bigger than half my monthly one?

This tool spreads your loan over the same number of years no matter which frequency you pick. It divides your yearly rate by 26 for fortnightly or 52 for weekly, then works out a payment that clears the loan on time.

Paying half your monthly amount every fortnight is different. That pays extra each year. To copy that, add the difference in the extra repayment box.

Does choosing Investment change my repayment?

No. It only labels your results as an investment loan. Lenders usually charge investors a higher rate, so type that higher rate in the interest rate box yourself.

Are fees like LMI, stamp duty and yearly package fees included?

No. The results show loan repayments only. Fees are not added.

If you know your comparison rate, type it in. It gives you a rough idea of the cost once most standard fees are counted.

Do I have to press Calculate every time?

No. The results update as soon as you change a number or tap a button. The Calculate button is there if you want to refresh the results yourself.

What does the loan end date mean?

It is the month your loan should be fully paid off, counting from today. If you add extra repayments, an offset or a lump sum, this date moves closer.

Why do the total interest and total repayments change when I add an offset?

The top tiles always show your real plan, including extras. An offset lowers the balance interest is charged on, so total interest drops.

Your headline repayment stays the same, because your set payment does not change. You just clear the loan sooner.

What is the blended effective rate?

It shows up when you turn on a split loan. It is one average rate that mixes your fixed rate and variable rate, weighted by how much money sits on each.

Example: a big fixed portion at a low rate pulls the blended rate down.

What happens after my fixed period ends in a split loan?

The tool moves your whole loan onto the variable rate you typed in. Your repayment is worked out again from that point to clear the balance by the end of the term.

Why can't I set the interest only period as long as my loan term?

You need at least some time to pay the loan back. The tool keeps the interest only years shorter than the loan term, so there is room to repay the principal after it ends.

Why does my repayment jump so much after interest only ends?

Because your balance never went down. You still owe the full amount, but now you have fewer years left to pay it off, so each payment must be larger.

What is the red dot on the balance chart?

It marks the year you make your lump sum payment. You can see the balance drop at that point and the line finish earlier.

Does the affordability meter use pay before or after tax?

Before tax. Pick your gross monthly income, which is your pay before tax is taken out. Under 28% is comfortable, 28% to 35% is tight, and over 35% is stretched.

Why do the rate change buttons show a bigger repayment but I did not change my rate?

That section is a test only. It shows what your payment would be if your rate moved up or down. Your main results stay on the rate you typed in. Tap None / reset to clear it.

Can I enter a loan term longer than 30 years?

No. The limit is 30 years, which is the longest term most Australian lenders offer on a standard home loan.

Why is most of my early payment interest and not principal?

Interest is charged on what you still owe. At the start you owe the most, so the interest part is big. As the balance falls, less goes to interest and more goes to principal. The donut chart and year table show this split.

Can I save or print my results?

Yes. Press Print summary. You get a clean page with your loan details, repayment, total interest and end date. You can print it or save it as a PDF.

Is my information stored?

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

How close will these numbers be to my real repayment?

They are good estimates. Real repayments can differ because of fees, rounding by your lender, the exact day your loan starts, and rate changes over time. Always check the final figures with your lender.