Auto Loan Amortization Calculator

This auto loan amortization calculator builds the complete payment schedule for a vehicle loan — factoring in sales tax, down payment, and trade-in value to arrive at the actual amount financed, then breaking every monthly payment into principal and interest down to a zero balance.

Worked example (the defaults): a $35,000 vehicle with a $5,000 down payment, no trade-in, and 6.5% sales tax finances $32,275.00 — the price plus $2,275 of tax, minus the down payment. At 7.1% APR over 5 years, that comes to a monthly payment of $640.61 and $6,161.45 in total interest over the loan.

Sales tax and trade-in value are easy to overlook when comparing loan offers, but they change the actual principal you're financing — and therefore every number downstream. If you're deciding whether to pay this loan off faster, run the same balance through the Car Loan Payoff Calculator to see the effect of extra monthly payments.

The amount you actually finance isn't just the vehicle price. Most states tax the vehicle price minus any trade-in credit, and that tax is commonly rolled into the loan rather than paid up front:

Once the financed amount is set, the loan amortizes with the standard installment formula used across auto lending, per the CFPB's auto loan guidance:

Each month, interest accrues on the remaining balance and the rest of the fixed payment reduces principal — the same declining-interest, rising-principal pattern as any amortized loan, shown here row by row for the full term.

Whether trade-in value reduces your taxable amount depends entirely on your state — most states give a full trade-in tax credit, a handful give none, and a few cap it. This calculator applies tax to price minus trade-in, which matches the majority of states, but check your state DMV's rule before financing if you're trading in a vehicle, since a no-credit state changes the taxed amount and therefore the financed principal.

Some states also charge tax on the down payment portion differently, or add separate title, registration, and doc fees outside the sales tax rate — this tool models sales tax specifically, so add any flat fees to your down payment field to route them out of the financed principal if you're paying them at signing.

This calculator subtracts your trade-in before applying sales tax. Some states tax only the difference and others tax the full price, so check how your state treats trade-ins.