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Auto loan calculator.See what the dealer skips.
Compare 60, 72, and 84-month loans side by side. See total interest, monthly payment, and the months your car is worth less than what you owe.
What this actually costs
Over 72 months at 7.50% APR, you'll pay $8,510 in interest — that's 24% on top of the car's price. You'll be underwater for 12 of the 72 months (17% of the loan), meaning you can't sell or trade without bringing cash to closing.
Monthly payment: $600.83 · Total cost over the term: $43,260
Depreciation curve: 15% in year 1, 15% year 2, 12% year 3, 10%/yr after. Industry average per Edmunds and Carfax. Your car may depreciate faster or slower depending on make, model, mileage, and condition.
Why this one
Most calculators stop at the payment.This one keeps going.
Three terms, one screen
60, 72, and 84-month side by side. Same APR, same car. The 84-month payment is always the most attractive in isolation — putting them next to each other is what makes the trade-off visible.
The underwater months
Your loan balance vs. your car's depreciated value, plotted over time. The shaded region is the period you can't sell or trade without bringing cash to closing. On a 72-month loan at average APR, that's often 30+ months.
Plain-English summary
A sentence at the top that tells you what you're actually agreeing to: total interest, percentage of the car's price, underwater duration. No tabs, no exports, no rate-quote pop-ups.
How it works
The math behind the chart.
Monthly payment uses the standard amortization formula: PMT = P × (r(1+r)n) / ((1+r)n − 1), where P is the principal (price + tax + fees + rollover − down payment − trade-in), r is the monthly rate (APR ÷ 12), and n is the term in months.
Loan balance at any given month is computed as P × (1+r)m − PMT × ((1+r)m − 1) / r. That closed-form remainder is what the black line on the chart tracks.
Depreciated value follows the industry-average curve: 15% in year 1, 15% in year 2, 12% in year 3, 10% per year after that. The grey line on the chart. Your car may depreciate faster or slower depending on make, model, mileage, and condition — luxury sedans and EVs are typically faster; Toyotas, Hondas, and popular trucks are slower.
Underwater months = the count of months where the loan balance line is above the depreciated value line. This is the period during which you would owe the lender money to walk away from the car — sell it, trade it, or total it without GAP insurance. On a 72 or 84-month loan at 7%+ APR with standard depreciation, this often covers more than half the loan's life.
Negative-equity rollover works by adding what you still owe on your trade-in to the new loan principal. If your trade is worth $12,000 and you owe $18,000, $6,000 follows you into the next loan, financed at the new APR over the new term. Put your trade payoff in "Still owed on trade-in" and the dealer's offer in "Trade-in value" — the rollover math handles itself.
What this calculator can't see is inside the actual loan contract: prepayment penalties, mandatory arbitration, force-placed insurance terms, GAP and VSC markups, dealer add-ons baked into the finance amount, and the holder rule that lets you raise dealer defenses against the lender. Once the math works on paper, scan the contract to flag the clauses the calculator misses.
Considering leasing instead?
See the money factor markup, in plain English.
The car lease calculator converts money factor to APR and flags the dealer markup against this month's captive base rates. Compare both before signing either.
Next step
The math is the easy part.
The contract is the hard part. Photograph or paste the loan agreement before you sign. Redline flags prepayment penalties, arbitration clauses, GAP markups, and the dealer add-ons baked into your finance amount — in plain English, in under a minute.
Questions
Auto loan calculator FAQ.
How is this calculator different from Bankrate or NerdWallet?+
Most auto loan calculators show you a monthly payment and stop. This one shows three things they skip: a side-by-side comparison of 60, 72, and 84-month terms (so you can see what stretching the loan actually costs in interest), the months your loan balance is higher than the car's depreciated value (the period you can't sell or trade without bringing cash to closing), and a plain-English summary of what the loan really costs you over the full term. Bankrate and NerdWallet are excellent at the math — they're optimized to funnel you to a lender. This tool is optimized to show you the trap before you sign.
What does 'underwater' mean on an auto loan?+
Underwater (also called 'upside-down' or 'negative equity') means you owe more on the loan than the car is currently worth. If you tried to sell the car or trade it in, the sale price wouldn't cover the loan payoff, so you'd have to bring cash to closing to get out. On a 72 or 84-month loan, most buyers are underwater for the majority of the loan's life. Experian Q1 2026 data shows 40.7% of buyers with negative equity choose 84-month terms — the structural feature that makes the next loan worse, not better.
How accurate is the depreciation curve?+
The calculator uses an industry-average curve: 15% in year 1, 15% in year 2, 12% in year 3, then 10% per year after that. This matches the published averages from Edmunds, Carfax, and CarEdge. Your specific car may depreciate faster (luxury sedans, EVs with battery degradation, vehicles with high mileage) or slower (Toyotas, Hondas, popular trucks). For a make-and-model-specific curve, check the KBB or Edmunds 5-year depreciation estimator and adjust your expectations.
Is an 84-month auto loan ever a good idea?+
Rarely. Three scenarios where it can pencil out: (1) you have a sub-4% APR (almost no one does in 2026 unless it's a captive-finance promo), (2) you plan to hold the car for 7+ years past the payoff, or (3) you're using the long term as a tactical bridge and plan to pay it off early. For most buyers, the honest alternative is a less expensive car on a 48 or 60-month loan, not the same car on a stretched term. See our 84-month walkthrough for the math.
Why is the sales tax applied to the price minus trade-in?+
Most US states tax the net price after trade-in credit — you only pay sales tax on the difference between the new car and what the dealer is crediting for your trade. A handful of states (California, Hawaii, Maryland, Michigan, Virginia, and a few others) tax the full purchase price. If you're in one of those states, the calculator will slightly understate your tax. The error is small for most buyers; for a more precise figure, check your state's DMV or revenue department website.
What about rolling negative equity into the new loan?+
If you owe more on your trade-in than the dealer is giving you for it, that gap (the negative equity) gets added to your new loan. Put the trade-in's payoff amount in 'Still owed on trade-in' and the dealer's offer in 'Trade-in value' — the calculator rolls the difference into the principal. Note that rolling negative equity forward stretches your underwater period on the next loan and is a primary reason buyers stay upside-down through three or four vehicles in a row.
Does this replace reading the loan contract?+
No. The calculator shows you the math; the contract is where the surprises live. Mandatory arbitration clauses, prepayment penalties, GAP insurance markups, dealer-add-on fees, and force-placed insurance terms can change the deal's economics by thousands of dollars. Once you've decided the loan makes sense on paper, scan the actual contract in Redline to flag the clauses that aren't on the calculator.