Truck Payment Calculator
Monthly payment, total interest, and the all-in cost of that truck — run it in the parking lot before you sign anything inside.
Enter the deal and hit RUN THE DEAL
How this calculator works
This is standard loan amortization — the same math behind a mortgage, run at equipment-lender rates. The calculator subtracts your down payment from the out-the-door price to get the amount financed, converts the APR to a monthly rate, and solves for the fixed payment that retires the loan over your term. Then it shows the two numbers the finance office doesn't lead with: total interest over the life of the loan, and the all-in cost of the truck once every payment has cleared.
where r = APR ÷ 12, n = months, loan = price − down
If the interest works out to more than 40% of the amount you borrowed, the ticket stamps it STEEP — not because the payment won't fit, but because that's the sign to shop the rate or shorten the term before signing. Add your monthly miles and it also prints the payment per mile, ready to drop into your cost per mile.
Two worked examples
Example 1 — a clean deal on a used Kenworth
An $85,000 truck with $15,000 down leaves $70,000 financed. At 12% APR over 48 months the payment lands at $1,843 a month, total interest about $18,500, all-in cost roughly $103,500. Running 9,500 miles a month that payment is 19 cents a mile — a number your lanes can carry if your break-even stays under control. Four years from now the note is gone and the truck, treated right, still has life to give.
Example 2 — same truck, worse paper
Same $70,000 financed, but a new authority with thin credit gets 20% APR, and the finance office "helps" by stretching to 60 months to hold the payment down: $1,855 a month. Look at that closely — twelve dollars more per month than Example 1. The damage hides underneath: about $41,300 in interest, more than double, and you're chained to the note a full extra year on a truck that'll be pushing 700,000 miles before it's yours. Same truck, same payment, $23,000 difference. That's why you never shop the payment.
From the road
The first question at every dealer is "what payment are you looking for?" — and it's the wrong question on purpose. A payment can be manufactured out of any price by stretching the term; the APR and the out-the-door number are where the deal actually lives. Get both in writing, then run them here in the parking lot before you go back inside. And price the whole truck: doc fees, extended warranties rolled into the note, and on new trucks the 12% federal excise tax all ride along and collect interest for years.
Budget for the truck after the truck, too. A used Class 8 coming off someone's fleet has a way of announcing its needs in the first ninety days — eight drive tires that all age together, batteries, an aftertreatment system with opinions. The payment you can afford is the one that still fits in a month where the truck also took $4,000 from you. Before you sign anything, work through the full deal on paper — the whole truck, not just the loan.
FAQ
What APR should I expect on a truck loan?
Established owner-ops with good credit: often 7–12%. New authority or bruised credit: 15–25%+ from equipment finance companies. Get the APR in writing — the payment alone hides it.
How much down do lenders want?
Usually 10–30% on a used Class 8. More down = smaller loan and less time upside-down on a fast-depreciating asset.
Longer term for a lower payment — worth it?
The payment drops but total interest climbs, and you risk owing on a truck that's out of warranty. Match the term to the truck's realistic remaining life.
Dealer financing or my own bank?
Shop both. Dealers route through equipment finance companies and may mark up the rate; a bank or credit union that knows you can beat it. A payment quote without an APR is a number designed to hide another number.
What about carrier lease-purchase deals?
Read them like they're radioactive: you carry the payments, escrow, and risk while the company you owe controls your loads and rates. Work out the effective interest against what the truck really sells for — it's often past anything a lender would print.
How much cash should I keep after buying?
Enough to survive the truck's first bad month: a reserve covering one major repair ($5,000–$10,000) plus a month of fixed costs. Used trucks announce their needs early.