Auto loan calculator
The price on the sticker isn’t the number that hits your budget every month - the loan amount is what’s left after a down payment and trade-in, spread across a rate and a term. This calculator turns those inputs into a monthly payment and the total interest the loan will cost.
How the math works
The amount financed is the vehicle price minus your down payment and trade-in credit. That balance runs through the standard amortization formula M = P·r·(1+r)ⁿ ÷ ((1+r)ⁿ − 1) to produce a level monthly payment, then the calculator multiplies the payment by the number of months to show total interest over the life of the loan. A longer term lowers the monthly payment but stretches out interest - running the same numbers at a shorter term shows the trade-off directly.
Related reading
How interest on a car loan actually gets calculated each month walks through the mechanics behind this calculator’s output, and how the size of a down payment affects car loan terms explains why the down payment field moves the payment as much as it does. Why new car loans usually have lower rates than used car loans covers what typically drives the rate you’re quoted, and what trade-offs come with choosing a longer car loan term digs into the term-length decision this tool makes visible.
The formula this calculator uses
financed = price - deposit - trade-in
r = annual rate / 100 / 12
n = years * 12
payment = financed * r * (1+r)^n / ((1+r)^n - 1)
interest = payment * n - financed
What it assumes without asking
- A fixed rate for the whole term
- The trade-in is worth what you entered and carries no loan of its own
- Payments start one month after the loan does, and none are missed
One example, computed in full: $25,000 financed at 7.00%
| Term | Monthly payment | Total repaid | Total interest | Interest per $1,000 |
|---|---|---|---|---|
| 3 years | $771.93 | $27,789 | $2,789.39 | $111.58 |
| 4 years | $598.66 | $28,735 | $3,735.49 | $149.42 |
| 5 years | $495.03 | $29,702 | $4,701.80 | $188.07 |
| 6 years | $426.23 | $30,688 | $5,688.21 | $227.53 |
| 7 years | $377.32 | $31,695 | $6,694.63 | $267.79 |
What this calculator does not model
- Tax, title, registration and dealer fees, which are usually added to the amount financed and would raise every figure above
- Negative equity rolled in from a previous loan
- That the car is losing value the whole time, which is why a long term can leave you owing more than it is worth
The guide behind this tool
A number on its own does not tell you what to do with it. The extra row worth reading is the last one: stretching the same loan from three years to seven roughly triples the interest per $1,000 borrowed. Good debt against bad debt covers the four questions worth asking before signing.
Sources & further reading
This tool is a general educational estimate, not financial advice or a loan offer. Real quotes vary by credit, lender, fees, and taxes. See our disclaimer.