Enter the total loan amount — that's the vehicle price minus any down payment and trade-in value — along with the annual interest rate and loan term in months. The calculator uses the standard amortization formula to give you your fixed monthly payment and the total interest you'll pay over the life of the loan.
M = P × r(1+r)^n / ((1+r)^n − 1), where P is the loan principal, r is the monthly interest rate (annual rate ÷ 12), and n is the number of monthly payments.
Auto loan terms typically run 24 to 84 months. The most important thing this calculator reveals isn't the monthly payment — it's the total interest paid. Dealers and lenders lead with monthly payment because it's the number that feels manageable. Always look at total cost when comparing offers.
A practical tip: run the numbers before you visit a dealership. Knowing your target monthly payment and what rate you qualify for puts you in a much stronger negotiating position than working backwards from a payment the dealer presents you.
Suppose you're financing a $25,000 used car with a $3,000 down payment, leaving a loan amount of $22,000. Your lender offers a 6% annual interest rate over a 60-month term.
The monthly rate is 6% ÷ 12 = 0.5%. Using the amortization formula, your monthly payment would be approximately $424.94. Over 60 months you'd repay a total of $25,496 — meaning about $3,496 in interest over the life of the loan.
If you extended the same loan to 72 months, the monthly payment would drop to roughly $365.45, but total interest paid would rise to around $4,312 — an extra $816 just for the longer term. This is why it's worth running both scenarios before committing to a loan offer.
Yes — almost always. Getting pre-approved through your bank or credit union takes 30 minutes and gives you a rate benchmark the dealer has to beat. Dealership financing (through the manufacturer's captive lender or a third-party bank) is convenient but often carries a markup. The dealer earns a commission on the rate spread — the difference between the rate you're offered and the rate the lender actually requires. A pre-approval eliminates that leverage entirely.
New car loans consistently carry lower interest rates than used car loans. Lenders consider new cars lower risk because their value is easier to establish and they're less likely to have hidden mechanical issues. The gap varies by lender and credit score but is typically 1–3 percentage points. On a $25,000 loan over 60 months, a 2% rate difference adds up to roughly $1,300 in extra interest — worth factoring into the new vs. used cost comparison.
Your trade-in value is applied as a reduction to the purchase price before financing, which directly lowers your loan principal. If your trade-in is worth $8,000 and you're buying a $30,000 car, you only need to finance $22,000 (minus any additional down payment). The catch: if you still owe money on the trade-in, that negative equity is typically rolled into the new loan, increasing your principal and compounding the underwater risk on the new vehicle.
GAP (Guaranteed Asset Protection) insurance covers the difference between what your car insurance pays out if the vehicle is totaled or stolen and what you still owe on the loan. Because cars depreciate faster than loans pay down — especially on longer terms — many borrowers are underwater for the first few years of ownership. If you're financing over 60 months, putting less than 20% down, or buying a vehicle that depreciates quickly, GAP insurance is worth the cost. Skip it if you're on a short term with a large down payment and the loan balance will track closely with the car's value.
No — principal and interest only. Your actual financed amount will typically be higher once you include sales tax, dealer fees, registration, and any add-ons like extended warranties or GAP insurance. Always ask for the out-the-door price in writing and use that figure as your loan amount for an accurate payment estimate.
48 months is the sweet spot for most buyers — higher monthly payment than 60 or 72 months, but significantly less total interest and much lower risk of going underwater on a depreciating asset. If cash flow is tight, 60 months is a reasonable compromise. 72 months or longer should generally be a last resort — the total cost climbs substantially and you're likely to owe more than the car is worth for years. As a rule of thumb, don't finance a vehicle for longer than you realistically plan to own it.
In order of impact: increase your down payment or trade-in to reduce the principal; negotiate the vehicle price down before discussing financing; get pre-approved at a credit union to secure a lower rate; or extend the loan term. The last option costs the most over time — use this calculator to see exactly how much before committing.
A car is a depreciating asset — it loses value the moment you drive it off the lot. Your loan balance, meanwhile, shrinks slowly at first (early payments are mostly interest). This mismatch creates a window where you can owe significantly more on the loan than the car is actually worth. That's called being underwater, or having negative equity.
It matters most if the car is totaled, stolen, or you need to sell or trade it in before the loan is paid off. Your insurance pays out market value — not your remaining loan balance. Without GAP insurance, you'd owe the difference out of pocket.
Here's how it typically plays out on a $30,000 car financed over 72 months at 7%, compared against average depreciation for a typical new vehicle:
| Month | Approx. Loan Balance | Approx. Car Value | Equity / Gap |
|---|---|---|---|
| 0 (purchase) | $30,000 | $27,000 | −$3,000 |
| 12 months | $25,900 | $22,500 | −$3,400 |
| 24 months | $21,500 | $18,900 | −$2,600 |
| 36 months | $16,800 | $16,200 | −$600 |
| 48 months | $11,700 | $13,800 | +$2,100 |
On a 72-month loan, most borrowers are underwater for the first three-plus years. A shorter term (48 months) closes that gap much faster. If you're financing a new car over 60 months or more, GAP insurance is worth considering — it covers the difference between what insurance pays and what you still owe if the car is written off.