Loan Calculator

Before you sign for a personal loan, you should know four numbers: the regular repayment, the total interest, the full cost including fees, and how much extra repayments could save you. This Australian loan calculator produces all four — plus a comparison rate estimate and a year-by-year amortisation schedule — for loans between $1,000 and$100,000 over terms of one to ten years, with monthly, fortnightly or weekly repayments.

How It Works

The calculator applies the standard reducing-balance amortisation formula used by Australian lenders. Your annual rate is divided by the number of repayment periods per year (12 monthly, 26 fortnightly, 52 weekly) to get the periodic rate, and the repayment that exactly clears the balance over the term is solved from it.

Fees are then layered on: an establishment fee (up to $2,000) plus a monthly account-keeping fee (up to$50) multiplied across the term give total fees, and total cost is all repayments plus all fees. The comparison rate is estimated on the basis Australian law prescribes — a $30,000 loan over five years — folding the fees you entered into a single annual percentage so offers can be compared apples-to-apples.

Finally, if you enter an extra repayment per period, the tool simulates paying the loan off with that additional amount and reports the interest saved. A verdict summarizes the loan's cost: total interest under 20% of the amount borrowed rates as great value, under 40% as moderate, and above that as high cost.

The Formula

$M = P \times \frac{r(1 + r)^{n}}{(1 + r)^{n} - 1}$

where $M$ is the periodic repayment, $P$ the amount borrowed, $r$ the periodic rate (annual rate ÷ periods per year), and $n$ the total number of repayments.

Input Parameters

| Parameter | Unit | Description | |---|---|---| | Loan Amount | Currency (AUD) | $1,000 to$100,000. | | Interest Rate | % per year | Between 0.1% and 50%. | | Loan Term | Years | 1 to 10 years. | | Repayment Frequency | Choice | Monthly (12), fortnightly (26) or weekly (52). | | Establishment Fee | Currency | One-off upfront fee, $0 to$2,000 (optional). | | Monthly Fee | Currency / month | Account-keeping fee, $0 to$50 (optional). | | Extra Repayment | Currency | Extra paid per repayment period, $0 to$5,000 (optional). |

Worked Example

You borrow $20,000 at 9.5$200 establishment fee and a $10 monthly account-keeping fee.

• Monthly repayment: **$420.04** —$25,202.23 in repayments over the 60 months.
• Total interest: $5,202.23, which is 26.0% of the amount borrowed — the tool's verdict rates this a moderate-cost loan and suggests a shorter term or extra repayments.
• Fees: $200 + ($10 × 60) = $800**, bringing the **total cost to$26,002.23.
• Comparison rate: 10.40% — the 9.5% headline rate plus the effect of those $800 in fees, expressed as a single rate on the standard$30,000, five-year basis. The 0.90-point gap between the two rates is the fees, made visible.
• **With an extra $50 a month:** total interest falls to$4,484.56 — $717.67 saved — and the loan clears in 53 months instead of 60, seven months early.

Switching the same loan to fortnightly repayments (without extras) gives a repayment of $193.54 every two weeks and total interest of$5,160.47 — a modest $41.76 saving, because this tool amortizes genuinely over 26 periods a year rather than applying the "half the monthly payment" shortcut; the benefit comes from money reaching the balance sooner, not from paying more per year.

Interpreting the Results

• Total cost, not the repayment, is the comparison number. A longer term always shrinks the repayment; only the total cost shows what that comfort charges you.
• The comparison rate exists because headline rates hide fees. Two loans at the same rate with different fees are not the same loan — check the comparison rate on any real offer against the rate advertised, exactly as this tool estimates it on the standard $30,000, five-year basis.
• The amortisation schedule shows the balance at each year-end with the year's principal and interest split. Early years are interest-heavy: on the example loan, year one repays far less principal than year five, which is why extra repayments early in the term save the most.

Fixed vs Variable Rates

A fixed rate keeps repayments identical for the term — easy to budget — but Australian fixed loans typically cap extra repayments and can charge break costs for early payout. A variable rate moves with the market and usually allows unlimited extra repayments and redraw. This calculator assumes one constant rate for the whole term, whichever type you are modeling; if you expect your variable rate to change, run the numbers again at the higher rate to see the worst case.

Limitations

• Constant rate, no break costs or exit fees, and no allowance for repayment holidays or rate changes mid-term.
• The comparison rate is an estimate produced by the tool's methodology on the standard basis; a lender's official comparison rate for your actual loan amount and term may differ slightly, and the tool's estimate does not vary with the amount you enter.
• Fees are capped at the input limits above; a loan with fees beyond them cannot be modeled exactly.

Frequently Asked Questions

What is a comparison rate?

It is a single percentage that expresses the interest rate plus most upfront and ongoing fees, calculated in Australia on a standard $30,000 loan over five years under the National Consumer Credit Protection Act. Lenders must display it next to any advertised rate. Use it — not the headline rate — to compare offers.

How do extra repayments save so much?

Interest is charged on the outstanding balance. Every extra dollar reduces that balance from the day it is paid, so it removes not just itself but all the interest it would have attracted for the rest of the term. In the worked example, $50 a month —$2,650 actually paid before the loan ends early — removes $717.67 of interest.

Why does fortnightly save less here than I have heard?

The famous fortnightly trick — paying half your monthly repayment every two weeks — works because it smuggles in a thirteenth monthly payment each year. This calculator instead computes a true fortnightly amortisation of the same loan, so the annual amount paid is almost unchanged and the saving is only the small timing benefit ($41.76 on the example). If your lender lets you set the fortnightly amount at half the monthly figure, your saving would be larger.