Finance calculators

CommBank Loan Calculator

Updated Nov 11, 2026 By Infinity Calculator Formulas Sources
Rate
Loan Type
Loan Details
Amount borrowed: $650,000
Total term: 30 years (360 months)
Nominal annual rate: 6.09%
Rate Type
A fixed rate stays the same for the term you lock in.
All results below recalculate for this frequency.
Repayment Type
Enabled when Interest Only is selected.
Pay It Off Faster
Added to every repayment: $200.00
Interest is charged on the balance minus the offset: $25,000
Lump Sum Payments
Each lump sum reduces the loan balance in the month you choose.
Fees & Affordability
Establishment, valuation and settlement costs.
Account keeping or service fee charged each period.
Used for the repayment-to-income indicator. Enter 0 to skip.
Scenario B (side-by-side comparison)
Monthly Repayment
$0.00
 
Total Interest Paid
$0.00
 
Total Amount Repaid
$0.00
 
Loan Paid Off
 
Interest Saved (vs no extras)
$0.00
 
Time Saved
 
Effective Annual Rate (EAR)
0.00%
 
Comparison Rate (incl. fees)
0.00%
 
Repayment Affordability Indicator
0%30%60%+
30% or less
 
Rate Rise Stress Test
Scheduled repayment and total interest if your interest rate rises, based on your current inputs.
Rate scenarioRateScheduled repaymentChange per periodTotal interest
Scenario A vs Scenario B
Scenario A: your main loan
Loan amount
Rate / Term
Repayment
Total interest
Total repaid
Scenario B
Loan amount
Rate / Term
Repayment
Total interest
Total repaid
 
What You Repay: Principal vs Interest
Outstanding Balance Over Time
Step-by-Step Solution
Amortisation Schedule

Introduction

This loan calculator shows you what a loan will really cost. Pick your loan type (home loan, personal loan, car loan, or business loan), then enter how much you want to borrow, your interest rate, and how long you need to pay it back. You get your repayment amount right away, plus the total interest you will pay over the life of the loan.

You can also see how to pay your loan off faster. Add extra money to each repayment, add a lump sum, or use an offset account. The calculator shows how much interest you save and how many years you cut off your loan.

Other things you can check:

  • Weekly, fortnightly, or monthly repayments
  • Interest only or principal and interest repayments
  • Comparison rate that includes upfront and ongoing fees
  • Rate rise stress test to see what happens if rates go up
  • Scenario B to compare two loans side by side
  • Full amortisation schedule showing every repayment

There is a step-by-step section too, so you can see the math behind each answer. Change any number and the results update straight away.

How to use our Loan Calculator

Enter your loan amount, term, interest rate and how you pay it back. The calculator shows your repayment, total interest, total cost, payoff date, and how much you can save with extra payments.

Loan Type: Pick Home, Personal, Car or Business. Each type fills in example rates and fees that you can change, and sets the limits for the amount and term.

Loan Amount: Type the amount you want to borrow, or drag the slider.

Loan Term: Enter how long you will take to pay the loan, then choose Years or Months.

Annual Interest Rate (%): Enter the yearly rate your lender charges.

Rate Type: Choose Fixed if your rate stays the same, or Variable if it can change.

Repayment Frequency: Choose weekly, fortnightly or monthly repayments.

Repayment Type: Choose Principal & Interest to pay the loan down, or Interest Only to pay just the interest for a while.

Interest-only period (years): If you picked Interest Only, choose how many years that lasts.

Extra Repayment: Add any extra money you will pay each period. Use the +$100, +$250 or +$500 buttons for a quick change.

Offset Account Balance: For home loans, enter your offset savings. This money cuts the balance that earns interest.

Lump Sum Payments: Click "Add lump sum", then enter the amount and the month you will pay it.

Upfront Fees ($): Enter set-up costs like application and valuation fees.

Ongoing Fee ($): Enter any fee charged with each repayment.

Gross Annual Household Income ($): Enter your total yearly income before tax to see if repayments fit your budget. Enter 0 to skip.

Scenario B: Turn this on to compare a second loan. Enter its amount, rate, term and extra repayment to see which loan costs less.

Click Calculate to see your results, charts and full repayment schedule. Use Reset to start again.

Understanding Your Loan

A loan is money you borrow from a bank and pay back over time. You pay back two things: the principal (the amount you borrowed) and the interest (what the bank charges you for lending it). The longer you take to pay, the more interest you pay in total.

The Main Parts of a Loan

  • Loan amount: How much you borrow.
  • Interest rate: The yearly percentage the bank charges.
  • Loan term: How long you have to pay it off, like 5 years or 30 years.
  • Repayment frequency: How often you pay (weekly, fortnightly, or monthly).

Fixed vs Variable Interest Rates

A fixed rate stays the same for a set time, so your repayments do not change.4 A variable rate can go up or down over time, and your lender decides when it changes.4 Fixed gives you certainty. Variable can save you money if rates drop, but it can cost more if rates rise.4

Principal and Interest vs Interest Only

With principal and interest repayments, you chip away at the debt every time you pay. With interest only, you just pay the interest for a set period. Your payments are smaller at first, but you still owe the full amount, and you pay more interest overall.3

Ways to Pay Your Loan Off Faster

  • Extra repayments: Paying a little more each time goes straight onto the principal and helps you pay off the loan faster.3 Even $50 extra a month can cut years off a home loan.
  • Offset account: A savings account linked to your home loan.3 If you owe $500,000 and have $25,000 in offset, you only pay interest on $475,000.
  • Lump sums: A bonus, tax refund, or gift dropped onto the loan lowers your balance right away, so less interest builds up after that.3
  • Pay more often: Weekly or fortnightly payments shrink the balance sooner, which shaves off interest.
  • Clear other debts first: If you carry card or personal debt, choose an order to pay it down.

Fees and the Comparison Rate

Loans often have upfront fees (like setting up the loan or valuing a property) and ongoing fees charged each period. The comparison rate mixes those fees into one percentage.1 It shows the true cost, so you can compare two loans fairly. A loan with a low rate but big fees may cost more than one with a slightly higher rate.

Can You Afford It?

Lenders look at how much of your income goes to repayments. The indicator above shows the share of your gross income that this loan's required repayments take, not counting extra repayments, and marks the 30% line. On an interest-only loan it uses the higher repayment that follows the interest-only period. Paying more than 30 per cent of household income in mortgage repayments and other housing costs is often described as mortgage stress.6 The higher your share, the harder it is to keep up if rates rise or your income drops. It is smart to test what happens if your rate goes up by as much as 3%, since rates change over the years.4 Keep an emergency fund as a buffer.

Common Loan Types

  • Home loan: Large amounts, long terms such as 25 or 30 years, and lower rates because your home is security.
  • Personal loan: Smaller amounts and terms of usually 1 to 7 years. Without security, the rate is usually higher.
  • Car loan: Can use the car as security. An unsecured car loan often has a higher rate than a secured one.
  • Business loan: Used for stock, gear, or growth, with terms and rates that depend on the business. Loan contracts can set limits on how well the business's earnings cover its debt payments, which is what the DSCR measures.

Formulas used

Periodic interest rate
r = \frac{\text{annual rate}\ (\%)}{100 \times p}
Number of repayments
n = \text{term in years} \times p
Scheduled repayment (amortising loan)
M = P \times \frac{r(1+r)^n}{(1+r)^n - 1}
Interest charged each period (with offset)
I_k = \max(0,\ B_k - \text{Offset}) \times r
Balance update with extra repayment and lump sum
B_{k+1} = B_k - \left[(M + \text{Extra}) - I_k + \text{Lump}_k\right]
Effective annual rate
EAR = \left[(1+r)^p - 1\right] \times 100\%
Comparison rate, principal and interest repayments (solve for r_c, then annualise)
P - F_{\text{upfront}} = (M + F_{\text{ongoing}}) \times \frac{1-(1+r_c)^{-n}}{r_c}, \qquad \text{Comparison rate} = r_c \times p \times 100\%
Repayment-to-income ratio (required repayment, without extra repayments)
\text{Ratio} = \frac{M_{\text{required}} \times p}{\text{Gross annual income}} \times 100\%

Frequently asked questions

How much interest will I pay on a $650,000 home loan?

At 6.09% over 30 years, monthly repayments are about $3,935 and you pay around $766,000 in interest. That is more than the amount you borrowed. Adding $200 extra each month pays the loan off about 3 years and 8 months sooner and cuts about $111,000 off that interest.

Why is the effective annual rate higher than my interest rate?

Interest is charged every period, not once a year. Each charge sits on top of the last one, which is called compounding. So a 6.09% rate paid monthly really costs about 6.26% a year. The EAR box shows this true yearly figure.

What does the comparison rate here include?

It rolls your upfront fees and your ongoing fee per repayment into the interest rate.1 Like a lender's comparison rate, it does not include costs such as early repayment fees or redraw fees.5 A lender's comparison rate is worked out for an example loan amount and term, and different amounts and terms give different comparison rates.5 The figure here is worked out for the loan you enter. Use it to compare two loans fairly.

Does an offset account lower my repayment?

On a principal and interest loan, no. Your repayment stays the same. Less of it goes to interest and more goes to the principal, so the loan finishes sooner and costs less overall.3 On an interest-only loan, the repayment is the interest, and you only pay interest on the balance minus the offset, so the offset lowers your interest-only repayment.

What happens when my interest-only period ends?

Your repayment jumps. You still owe the full amount, but now you must pay it off in fewer years. The results box shows the interest-only amount first, then the higher principal and interest amount that follows.

What is the rate rise stress test for?

It shows your repayment and total interest if your rate rises by 1%, 2% or 3%. This matters most on a variable rate. If a 3% rise looks too tight for your budget, think about borrowing less.

What does the loan-to-income multiple mean?

It is your loan amount divided by your gross yearly income. Borrow $650,000 on $150,000 income and the multiple is 4.3×. It counts only this loan, so any other debts you have are left out. APRA limits banks, allowing them to make up to 20 per cent of their new mortgage lending at debt of six times income or more.2 The limit took effect on 1 February 2026. It applies separately to owner-occupier and investor lending, and it does not cover bridging loans for owner-occupiers or loans to buy or build a new home.2

Do weekly repayments really save money?

Yes, a little. Paying more often means the balance drops sooner, so less interest builds up. The bigger win is paying half your monthly amount every fortnight. Because a year has 26 fortnights, that adds up to one extra monthly repayment each year.3 The Fortnightly option here works out a smaller fortnightly repayment, so to see this, add the difference as an Extra Repayment.

What is the difference between total interest and total amount repaid?

Total interest is just the bank's charge. Total amount repaid is the principal plus that interest, including any lump sums. The line under it adds your fees for the full cost.

Why does most of my early repayment go to interest?

Interest is charged on what you still owe, and that is highest at the start. As the balance falls, the interest share shrinks and the principal share grows. The amortisation schedule shows this swap period by period.

Can I make extra repayments on a fixed rate loan?

Often only up to a limit. Some fixed rate loans limit extra repayments, and you may be charged a break fee if you pay off the loan early or switch home loans.4 Check your contract before you commit to big extras.

Is it better to pick a shorter term or pay extra?

Both cut interest. A shorter term locks in the higher payment, which keeps you on track. Extra repayments give you the same saving but you can stop them if money gets tight. Test both with Scenario B.

Sources

  1. Comparison rate (glossary definition). Moneysmart, Australian Securities and Investments Commission. Accessed September 10, 2026.
  2. APRA to limit high debt-to-income home loans to constrain riskier lending. Australian Prudential Regulation Authority. 2025;Media release, 27 November 2025. Accessed October 7, 2026.
  3. Pay off your mortgage faster. Moneysmart, Australian Securities and Investments Commission. 2026;Last updated 9 September 2026. Accessed November 11, 2026.
  4. Fixed vs variable home loan interest rates. Moneysmart, Australian Securities and Investments Commission. 2026;Last updated 16 September 2026. Accessed November 11, 2026.
  5. National Consumer Credit Protection Regulations 2010, regulation 71: Comparison rate. Commonwealth of Australia. Regulation 71, subregulations (7) and (11). Accessed November 11, 2026.
  6. Mortgage stress, rental stress, housing affordability stress: what's the difference? Australian Housing and Urban Research Institute. 2019;AHURI Brief, 27 February 2019, Mortgage stress. Accessed November 11, 2026.

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