How to Calculate a Car Loan Payment (and Spot the Real Cost)

By HSP · Published October 20, 2026 · 7 min read · Money & Finance

Car dealers like to talk about the monthly payment, because a small monthly number feels affordable. Lenders and consumer agencies keep repeating the same advice: look at the total cost instead. This guide shows exactly how a car loan payment is calculated, step by step, so you can check any quote yourself. We also compare loan terms side by side, because that is where most of the hidden cost lives.

Step 1: Work out the amount you will actually borrow

The sticker price is not the loan amount. Start with the agreed selling price, including options, freight and dealer fees, and adjust it:

1. Subtract your trade-in. The value the dealer gives for your old car.
2. Add sales tax. In many places, including Canadian provinces according to the federal government's vehicle loan calculator, tax is charged on the price after the trade-in is deducted, which makes a trade-in worth a little more than its face value. Rules differ between US states, so check yours.
3. Subtract your down payment. Cash you pay up front.

Amount financed = price − trade-in + sales tax − down payment.

Example: a $32,000 car, a $5,000 trade-in, 13% sales tax (Ontario's HST rate) and $3,000 down. Tax is 13% of $27,000 = $3,510. Amount financed = $32,000 − $5,000 + $3,510 − $3,000 = $27,510. Licence and registration fees are usually paid separately, so leave them out unless you are rolling them into the loan.

Step 2: Apply the loan payment formula

Car loans are normally amortized: every monthly payment is the same, and each one pays the month's interest plus a bit of the balance. The standard formula is:

Payment = L × r ÷ (1 − (1 + r)⁻ⁿ)

• L = amount financed ($27,510)
• r = monthly interest rate = APR ÷ 12 ÷ 100 (6.99% → 0.005825)
• n = number of monthly payments (60)

Plugging in: (1.005825)⁻⁶⁰ ≈ 0.7058, so the bottom of the fraction is about 0.2942. Then 27,510 × 0.005825 ≈ 160.25, and 160.25 ÷ 0.2942 ≈ $544.60 a month. Over 60 months you pay $32,676, of which $5,166 is interest.

You do not need to do this by hand. Enter price 32,000, down payment 3,000, trade-in 5,000, tax 13, APR 6.99 and 60 months into our car loan calculator and it shows the same payment, the tax and the total interest instantly. If a quote lists an APR and an interest rate that differ, our guide on APR vs interest rate explains why. Use the APR, because it includes most lender fees.

Step 3: Compare loan terms, not just payments

Here is the same $27,510 loan at 6.99% over different terms:

Going from 5 years to 7 years lowers the payment by about $130 a month, which sounds great, but it adds roughly $2,190 of extra interest, and you are making payments for two more years. Canada's Financial Consumer Agency (FCAC) calls loans of 72 months or more "long-term" and warns that they raise the total cost of the car. Its advice is simple: choose the shortest term you can afford.

Step 4: Check the rate, because it matters as much as the term

On the same 60-month, $27,510 loan, the APR changes the cost like this:

Every two points of APR cost about $1,500 here. That is why it pays to get a pre-approval from your own bank or credit union before you visit the dealer. The US Consumer Financial Protection Bureau notes that loan terms, including the rate, can be negotiated. With a quote in hand you can compare offers properly. Our loan comparison calculator puts two offers side by side.

A 0% offer is worth a closer look, too. Sometimes the alternative is a cash rebate. Run both cases: the 0% loan at full price versus a lower price financed at your bank's rate. The cheaper total wins.

The negative equity trap

Cars lose value fast. The FCAC says a new car may be worth about 25% less after one year, and its own example assumes a 40% drop after two years. Compare that with how slowly a long loan is paid down. Using our example and the FCAC's 40% figure purely as an illustration:

• After 24 months the $32,000 car might be worth about $19,200.
• On the 60-month loan you would still owe about $17,640, slightly less than the car is worth.
• On the 84-month loan you would still owe about $20,970. That is more than the car is worth, which is called negative equity.

Negative equity becomes a real problem if you need to sell, if the car is written off in an accident, or if you trade it in early and the leftover debt gets rolled into your next loan. A bigger down payment and a shorter term are the two simplest protections.

Budget for the whole cost of owning the car

The loan is only part of the monthly bill. Add insurance, fuel or charging, parking, maintenance and tires. Our fuel cost calculator estimates what your commute will cost, and the guide on calculating fuel cost walks through the maths. If you are buying in the US, the sales tax calculator helps with Step 1. To see how each payment splits between interest and principal over time, read how to amortize a loan.

A quick checklist before you sign

• Know the out-the-door price, the APR, the term and the total cost, not just the monthly payment.
• Get at least one outside loan quote to compare with the dealer's offer.
• Read the disclosure statement. In Canada, lenders and dealers must give you one showing the total cost of borrowing.
• Ask whether there is a penalty for paying the loan off early.
• Say no to add-ons you do not want. Extended warranties, paint protection and similar extras raise the amount financed.

VSH take: when a salesperson asks "what monthly payment are you comfortable with?", answer with a total price instead. A payment target is easy to hit by quietly stretching the term, and that is exactly the move that costs you the most.

General information only, not financial advice. Example rates and figures are illustrative; your rate depends on your credit, the lender and the vehicle. Updated 20 October 2026.