Auto Loan Tool
Explore vehicle financing with deposits, trade-ins, rebates, taxes, fees and optional balloon payments. Compare monthly, fortnightly or weekly instalments, model extra repayments, review amortisation and balance charts, and export a detailed schedule or summary.
| # | Date | Payment | Principal | Interest | Balance |
|---|
Table of Contents
Highlights
- Flexible monthly, fortnightly and weekly repayment estimates
- Deposit, trade-in equity and rebate adjustments
- Configurable sales tax and dealer fee treatment
- Balloon payments and extra repayment savings
- Interactive balance chart, amortisation table and CSV/JSON exports
How Auto Loan Tool Works?
The amount financed starts with the vehicle price, subtracts the deposit, net trade-in value and rebate, then adds sales tax and fees only when they are financed. Net trade-in value equals the trade-in allowance less any outstanding finance. Tax can be calculated on the full vehicle price, on the price less trade-in value, or excluded.
Here L is the financed balance, V the price, D the down payment, T the trade-in allowance, O the outstanding trade-in debt, R the rebate and F financed tax and fees (zero if paid up front). The payment frequency determines the periodic interest rate and the number of instalments.
Here f is 12, 26 or 52 payments per year and m is the term in months. A balloon amount reduces regular instalments but remains payable with the final instalment.
P is the regular instalment and B is the balloon amount. When the interest rate is zero, the regular instalment is (L − B) / n. Each period's interest is the opening balance multiplied by r; the remaining payment reduces principal. Optional extra payments increase principal repayment and can shorten the loan. The final instalment settles the entire outstanding balance.
| Output | What it represents |
|---|---|
| Regular instalment | Calculated payment before optional extra payments |
| Total interest | Sum of periodic interest in the accelerated repayment schedule |
| Interest saved | Difference between standard and extra-payment interest totals |
| Payoff date | Date of the final scheduled or accelerated payment |
| Total cash outlay | Cash deposit and any up-front tax or fees, plus all loan payments |
Practical Use Cases
First-time car buyers: Estimate instalments after choosing a deposit and term, then see the overall interest cost before agreeing to finance.
Trade-in customers: Include the value of an existing vehicle and any remaining loan balance to estimate the net credit towards a replacement.
Budget-conscious households: Compare monthly, fortnightly and weekly repayment frequencies, and examine the cash required at purchase.
Borrowers making extra repayments: Add an extra amount each period to examine potential interest savings and an earlier payoff date.
Buyers considering balloon finance: Explore how a future balloon amount reduces ordinary instalments but increases the amount due at the end of the term.
Vehicle dealers and advisers: Prepare illustrated finance scenarios and export a repayment schedule or summary for further discussion.
Accuracy and Limitations
Figures follow a fixed APR divided by 12, 26 or 52 payment periods per year, with interest applied to the outstanding balance at each instalment. This is an estimate rather than a lender quotation: actual contracts may use daily accrual, different rounding, changing rates, fees outside the entered amount, or different payment-date rules. The model uses the selected tax treatment without checking local eligibility; repayments and balance figures are rounded for display. Fortnightly and weekly payments use 14-day and 7-day dates, while periodic rates remain fixed; the first payment date does not add separate pre-payment interest. The displayed total cash outlay does not separately count any existing trade-in debt settled outside the model.
