How to use this car loan calculator
A car payment depends on more than the sticker price. This auto loan calculator combines the agreed vehicle price, down payment, gross trade-in value, old loan payoff, sales tax and financed fees. The result separates the financed balance from total interest, while advanced options make the assumed tax treatment explicit. Use the term comparison to see the payment and interest trade-off.
From purchase price to amount financed
Start with the vehicle price. Add estimated sales tax and fees you plan to finance. Subtract the cash down payment and trade-in credit. If you still owe money on the trade-in, add the outstanding old loan balance. This keeps the vehicle’s trade-in value and its existing debt separate instead of counting the same equity twice.
Trade-in equity and tax assumptions
Positive trade-in equity means the trade-in value exceeds its loan payoff; negative equity means more is owed than the vehicle is credited for. The tax selector offers two simple assumptions: tax on the full price, or tax on price minus gross trade value, bounded at zero. Local rules, rebates and eligibility conditions vary, so choose the assumption that matches your quote.
Compare the cost over the whole term
A longer term can reduce the scheduled monthly payment while increasing interest at the same rate. Optional extra principal payments can shorten the schedule. Neither the purchase model nor the loan total includes fuel, maintenance, vehicle insurance, future registration renewals or depreciation. Keep these ownership costs in a separate budget.
Car Loan formulas, explained
Trade-in equity
A negative amount indicates old debt that has not been covered by the trade-in credit.
Financed amount
Full-price tax = price × tax rate. Trade-credit tax = max(price − trade value, 0) × tax rate.
Auto loan payment
i is monthly interest and N is number of monthly payments; extra principal is optional.