Calculator inputs
Example data table
| Scenario | Vehicle Price | Down Payment | APR | Term | Trade-In | Taxes + Fees | Estimated Monthly Payment |
|---|---|---|---|---|---|---|---|
| Compact sedan | $22,000 | $3,000 | 5.90% | 48 months | $0 | $2,380 | $501.13 |
| Family SUV | $30,000 | $5,000 | 6.50% | 60 months | $2,000 | $3,090 | $490.91 |
| Pickup truck | $42,000 | $8,000 | 7.20% | 72 months | $3,000 | $4,400 | $581.22 |
Formula used
1. Down payment amount
If the user selects amount: Down = entered amount
If the user selects percent: Down = Vehicle Price × (Down % ÷ 100)
2. Taxable price
Taxable Price = max(Vehicle Price − Trade-In − Rebate, 0)
3. Sales tax amount
Sales Tax = Taxable Price × (Sales Tax Rate ÷ 100)
4. Loan amount
Loan Amount = Vehicle Price − Down Payment − Trade-In − Rebate + Sales Tax + Dealer Fees
5. Monthly payment
M = P × [r(1+r)^n] ÷ [(1+r)^n − 1]
Here, P is financed amount, r is monthly interest rate, and n is number of months.
6. Payment with extra amount
Actual Monthly Outflow = Base Monthly Payment + Extra Monthly Payment
7. Total interest
This is the sum of monthly interest across the amortization schedule.
How to use this calculator
Enter the vehicle price first. Then choose whether your down payment is an amount or a percentage.
Add trade-in value, rebate, local sales tax, and dealer fees. These values affect the financed balance.
Enter the APR and loan term in months. Add an extra monthly payment to test faster payoff scenarios.
Press Calculate Payment. Review the summary, graph, and amortization schedule. Use CSV or PDF export for reports or comparisons.
FAQs
1. How does a down payment change my car payment?
A larger down payment reduces the amount financed. That usually lowers monthly payment, total interest, and the chance of being upside down early in the loan.
2. Is it better to lower the term or raise the down payment?
Both can reduce interest. A shorter term lowers long-run finance cost more aggressively, while a bigger down payment lowers both payment size and financed balance immediately.
3. Does trade-in value reduce tax everywhere?
Not always. Some regions tax the price after trade-in credit, while others do not. This calculator assumes trade-in and rebate reduce taxable price, so check local rules.
4. What is APR in an auto loan?
APR is the yearly borrowing rate used to estimate interest cost. Higher APR increases the interest part of each payment, especially in early months.
5. Can extra monthly payments help significantly?
Yes. Even modest extra payments can shorten payoff time and cut interest. The schedule and savings outputs show how much faster the loan may end.
6. Why is my financed amount different from vehicle price?
The financed amount includes taxes and fees, then subtracts down payment, trade-in, and rebates. That final number is what the lender typically finances.
7. Is zero down always a bad idea?
Not always, but zero down means financing more money. That usually raises payment and interest, and may increase negative equity risk if the car depreciates quickly.
8. Should I compare monthly payment only?
No. Monthly payment matters, but total interest, payoff months, and financed balance matter too. A low payment can still hide a longer, more expensive loan.