How to Use This Auto Loan Calculator
- Enter the Vehicle Price — the sticker price or negotiated purchase price of the car.
- Enter your Down Payment — cash you pay upfront. More down means a smaller loan and less interest.
- Add your Trade-in Value if you have a vehicle to trade. This amount is subtracted from the price before financing.
- Set the Sales Tax rate for your state. Tax varies from 0% (Montana, Oregon) to over 10% (some California counties).
- Enter the Interest Rate your lender quotes. Credit score, loan term, and whether the car is new or used all affect your rate.
- Pick a Loan Term. The comparison table below the chart shows you the cost difference across all available terms.
The 20/4/10 Rule for Car Buyers
Financial planners suggest this simple guideline for keeping car payments manageable:
- 20% down payment so you’re not “upside down” from day one.
- 4-year (48 month) maximum term to limit interest costs and stay ahead of depreciation.
- 10% of gross income — your total vehicle costs (payment + insurance + gas) shouldn’t exceed 10% of monthly gross income.
On a $35,000 car with this rule, you'd put $7,000 down, finance $28,000 for 48 months, and need a monthly gross income of at least $7,000–$8,000 to stay comfortable.
New vs. Used Car: Financing Differences
| New Car | Used Car | |
|---|---|---|
| Typical Rate (good credit) | 4.5–6.5% | 6–9% |
| Typical Term | 48–72 months | 36–60 months |
| Depreciation (year 1) | 20–30% | 10–15% |
| Manufacturer Incentives | Often available | Rare |
Used cars cost less upfront, but higher interest rates and shorter terms can narrow the gap. A 2–3 year old certified pre-owned vehicle is often a solid middle ground: someone else absorbed the steepest depreciation, and the car usually still has warranty coverage.
How to Get a Lower Rate
- Check your credit first. Scores above 720 qualify you for the lowest rates. Fix errors on your credit report before applying.
- Get pre-approved. Apply at your bank or credit union before visiting the dealership. This gives you a baseline to negotiate against.
- Negotiate the price, not the payment. Dealers can stretch terms to hit any monthly number, but that costs you more in total interest.
- Skip the extras. Extended warranties, gap insurance, and add-ons sold in the finance office are often marked up 200–300%. Buy them separately if you want them.
- Consider a shorter term. Lenders typically offer lower rates for 36–48 month loans compared to 72–84 month loans.
Monthly Payment Formula
M = P × [r(1 + r)n] / [(1 + r)n − 1]
M = Monthly payment
P = Loan principal (Vehicle Price + Tax − Down Payment − Trade-in)
r = Monthly interest rate (APR ÷ 12)
n = Total number of payments
Total Interest by Loan Term ($30,000 Loan at 6%)
Total Cost of Car Ownership
The sticker price is just the beginning. True car ownership costs include several recurring expenses you should factor into your budget:
- Insurance: $1,200–$3,000/year for full coverage, depending on your age, driving record, and vehicle type.
- Gas: At 12,000 miles/year, 28 MPG, and $3.50/gallon, you spend about $1,500/year on fuel. EVs cost roughly $500–$800/year in electricity.
- Maintenance: Oil changes, tires, brakes, and repairs average $800–$1,200/year for newer cars, more for older vehicles.
- Depreciation: The largest hidden cost. A $35,000 new car may be worth $20,000 after just 3 years — that’s $5,000/year in lost value.
- Registration and fees: $100–$500/year depending on your state.
Add these up and a $35,000 car can cost $8,000–$12,000 per year beyond the monthly payment. Make sure this fits your budget — our salary converter helps translate your annual income to monthly take-home to see if the numbers work.
Underwater Loans and Negative Equity
You’re “underwater” (or “upside down”) when you owe more on the car than it’s worth. This happens most often when you make a small down payment on a long-term loan. New cars lose 20–30% of their value in the first year, so a buyer who puts 5% down on a 72-month loan can be underwater for the first 2–3 years.
To avoid negative equity: put at least 20% down, keep the term to 48–60 months, and consider gap insurance if your down payment is small. Check your overall debt health with our debt-to-income calculator.
Lease vs. Buy
Leasing gives you lower monthly payments and a new car every 2–3 years, but you never build equity and face mileage restrictions (typically 10,000–15,000 miles/year). Buying costs more monthly but you own the car and can drive it as long as you want. Over a 10-year period, buying is almost always cheaper — especially if you keep the car after paying it off. Use our loan payoff calculator to see how extra payments can shorten your loan and get you to debt-free car ownership faster.
Frequently Asked Questions
How to Use This Auto Loan Calculator
Enter the vehicle price, down payment, loan term, interest rate, and trade-in value. The calculator shows your monthly payment, total interest, and amortization schedule.
Formula & How It Works
Monthly Payment = (P – Down – Trade) × r / (1 – (1+r)^-n), where P is price, r is monthly rate, n is total months.
Calculation Example
Car price $32,000, $5,000 down, 5.9% APR, 60 months: Loan = $27,000. Monthly = $523. Total interest = $4,356. Total paid = $31,356.
Expert Tips
Keep the loan term to 48-60 months max to avoid being underwater. Get pre-approved before visiting dealerships. A 720+ credit score typically qualifies for the best rates.
How much car can I afford?
Use the 20/4/10 rule: put 20% down, finance for no more than 4 years, and keep total vehicle costs (payment + insurance + gas) under 10% of gross income. If you earn $5,000/month gross, aim for a total car cost under $500/month.
What is a good interest rate for a car loan right now?
In 2025–2026, competitive rates for new cars range from 4–7% for buyers with good credit (700+). Used car rates typically run 1–2% higher. Credit unions often beat dealership financing by 1–2 percentage points.
Should I choose a longer term for lower payments?
Longer terms (72–84 months) lower your payment but cost thousands more in interest. A 60-month loan at 6% on $30,000 costs about $4,800 in interest; stretching to 84 months raises that to $6,800. Longer terms also mean you could owe more than the car is worth for years.
Does a bigger down payment really make that much difference?
Absolutely. On a $35,000 car at 6.5% for 60 months: $3,500 down (10%) results in a $617/month payment and $5,500 in interest. Putting $7,000 down (20%) drops the payment to $551 and interest to $4,900, saving $600 in interest and $66/month.
Should I pay off my car loan early?
Paying early saves interest, but check your loan contract for prepayment penalties first. If your rate is low (under 4%), the money might earn more in a high-yield savings account or index fund. If your rate is over 5%, paying early is almost always worth it.