Auto Loan Calculator
Prices a car loan properly, including the trade-in complications that dealerships are good at obscuring.
Inputs
Principal — the amount being financed.
Interest Rate — your quoted or expected APR.
Loan Term (Months) — commonly 36, 48, 60, 72, or longer.
Down Payment — cash down.
Trade-In Value — what your current vehicle is worth.
Left on Trade-In — what you still owe on it.
The last two fields matter
If you owe more on your current car than it's worth, that difference is negative equity, and it doesn't disappear when you trade in. It gets added to the new loan.
This is where a lot of people quietly go wrong. You trade in a car worth $12,000 with $15,000 still owing, and the $3,000 gap rolls into your new financing — so you're now borrowing more than the new car costs, on a car that starts depreciating immediately.
Entering both figures makes this visible rather than something you discover on the paperwork.
Term length is the trap
Dealers negotiate on monthly payment because it's the number buyers care about, and monthly payment can be lowered indefinitely by extending the term.
A longer term means:
- ›A lower monthly payment
- ›Substantially more total interest
- ›Longer underwater — owing more than the car is worth, for years
That last one is what sets up the negative-equity problem on your next car. It's a cycle, and it starts with agreeing to a 72-month term because the payment looked fine.
Run the calculator at several terms and compare total cost rather than monthly payment.
Rate matters more than you'd think
A few percentage points on a five-year loan is a lot of money. Get a rate quoted by your own bank or credit union before you go to the dealer — you'll then have a number to compare their financing against, rather than accepting whatever's offered.
Add To Budget
This calculator has an Add To Budget button. Tap it and the loan goes into your Budget Builder inputs, with a Go To Budget shortcut to jump straight there.
Then rebuild. This is the step that changes minds: a payment that fits comfortably in your monthly cash flow can still push your debt-free date out significantly, and the plan will show you by how much.
Do it before you're sitting in the finance office.
The rest of the cost
The loan payment isn't the cost of the car. Also budget for:
- ›Insurance — which often rises sharply on a newer vehicle
- ›Fuel
- ›Maintenance and tires
- ›Registration and taxes
Add these to Expenses. A widely used guideline keeps total vehicle costs — payment, insurance, fuel, maintenance — under 15–20% of take-home pay. Use the Paycheck Calculator if you need that figure.