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How the Car Loan Calculator Works (With a Worked Example)

Updated 19 April 2026 · Loans and credit

Calculates car loan repayments, with or without a balloon payment. This guide walks through what each input means, the formula behind the answer and a worked example using typical Australian figures. You can follow along in the free Car Loan Calculator.

Why it matters

Personal credit in Australia covers car loans, personal loans, credit cards and buy now pay later. Lenders must quote a comparison rate alongside the headline rate, which bundles most fees into a single figure for a standard loan size.

What you need to enter

The calculator asks for 4 inputs. The table shows each one with the example value used later in this guide.

InputExample value
Loan amount ($)35000
Interest rate (%)8.5
Loan term (years)5
Balloon payment ($)0

The formula

Repayment uses the standard loan formula with the balloon as a lump sum at the end.

Worked example

Entering the example values above gives these results:

ResultValue
Monthly repayment$718.08
Total interest$8,084.72
Total cost$43,084.72

The headline figure is $718.08 (monthly repayment). Change any input in the calculator and every result updates instantly, so you can test different scenarios side by side.

How the monthly repayment changes with loan amount

The table below keeps every other input at the example value and moves only “Loan amount ($)” up and down by 10% and 20%. It shows how sensitive the monthly repayment is to that one figure.

Loan amount ($)Monthly repayment
28,000$574.46
31,500$646.27
35,000$718.08
38,500$789.89
42,000$861.69

At 28,000 the result is $574.46; at 42,000 it is $861.69. If a small change in this input moves the answer a lot, it is worth double-checking that figure before you rely on the result.

A practical tip

Compare comparison rates, not headline rates. The comparison rate includes most fees.

Keep going

Before relying on the number, read Getting the Most From a Car Loan Calculator: Tips and Common Errors. You might also find these guides useful:

Frequently asked questions

What is a comparison rate?
It combines the interest rate and most fees into one annual rate, usually based on a $30,000 loan over five years, to make loans easier to compare.
Do the results include fees?
Only where a fee input is shown. Add any known fees for a more realistic total.
Where can I get help with debt?
The National Debt Helpline (1800 007 007) offers free, confidential financial counselling.

Run your own numbers in the Car Loan Calculator.

Open the calculator

General information only. Rates and thresholds change, usually on 1 July. Confirm current figures with the ATO or the relevant authority, and get personal advice for decisions about your situation.